feat: provide a secret extension to store sensitive data (#3594)

#### What type of PR is this?
/kind feature
/milestone 2.4.x
/area core

#### What this PR does / why we need it:
提供 Secret 自定义模型用于存储敏感数据
例如：密码、token 等
参考自： https://kubernetes.io/docs/concepts/configuration/secret

#### Which issue(s) this PR fixes:

Fixes #3267

#### Does this PR introduce a user-facing change?
```release-note
提供 Secret 自定义模型用于存储敏感数据
```

api/src/main/java/run/halo/app/extension/Secret.java

@@ -0,0 +1,54 @@
+package run.halo.app.extension;
+
+import java.util.Map;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+/**
+ * Secret is a small piece of sensitive data which should be kept secret, such as a password,
+ * a token, or a key.
+ *
+ * @author guqing
+ * @see
+ * <a href="https://github.com/kubernetes/kubernetes/blob/f33498a8256b455b677ad4d30440869318b84204/staging/src/k8s.io/api/core/v1/types.go">kebernetes Secret</a>
+ * @since 2.0.0
+ */
+@Data
+@EqualsAndHashCode(callSuper = true)
+@GVK(group = "", version = "v1alpha1", kind = Secret.KIND, plural = "secrets", singular = "secret")
+public class Secret extends AbstractExtension {
+    public static final String KIND = "Secret";
+
+    public static final String SECRET_TYPE_OPAQUE = "Opaque";
+
+    public static final int MAX_SECRET_SIZE = 1024 * 1024;
+
+    /**
+     * Used to facilitate programmatic handling of secret data.
+     * More info:
+     * <a href="https://kubernetes.io/docs/concepts/configuration/secret/#secret-types">secret-types</a>
+     */
+    private String type;
+
+    /**
+     * <p>The total bytes of the values in
+     * the Data field must be less than {@link #MAX_SECRET_SIZE} bytes.</p>
+     * <p>{@code data} contains the secret data. Each key must consist of alphanumeric
+     * characters, '-', '_' or '.'. The serialized form of the secret data is a
+     * base64 encoded string, representing the arbitrary (possibly non-string)
+     * data value here. Described in
+     * <a href="https://tools.ietf.org/html/rfc4648#section-4">rfc4648#section-4</a>
+     * </p>
+     */
+    private Map<String, byte[]> data;
+
+    /**
+     * {@code stringData} allows specifying non-binary secret data in string form.
+     * It is provided as a write-only input field for convenience.
+     * All keys and values are merged into the data field on write, overwriting any existing
+     * values.
+     * The stringData field is never output when reading from the API.
+     */
+    private Map<String, String> stringData;
+
+}

api/src/test/java/run/halo/app/extension/SecretTest.java

@@ -0,0 +1,84 @@
+package run.halo.app.extension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
+import java.util.Map;
+import org.json.JSONException;
+import org.junit.jupiter.api.Test;
+import org.skyscreamer.jsonassert.JSONAssert;
+import run.halo.app.infra.utils.JsonUtils;
+
+/**
+ * Tests for {@link Secret}.
+ *
+ * @author guqing
+ * @since 2.4.0
+ */
+class SecretTest {
+
+    @Test
+    void serialize() throws JSONException {
+        Secret secret = new Secret();
+        secret.setMetadata(new Metadata());
+        secret.getMetadata().setName("test-secret");
+        secret.setType(Secret.SECRET_TYPE_OPAQUE);
+        secret.setData(Map.of("password", "admin".getBytes()));
+        String s = JsonUtils.objectToJson(secret);
+        JSONAssert.assertEquals(testJsonString(), s, true);
+    }
+
+    @Test
+    void deserialize() {
+        String s = testJsonString();
+        Secret secret = JsonUtils.jsonToObject(s, Secret.class);
+        assertThat(secret).isNotNull();
+        assertThat(secret.getMetadata().getName()).isEqualTo("test-secret");
+        assertThat(secret.getType()).isEqualTo(Secret.SECRET_TYPE_OPAQUE);
+        assertThat(secret.getData()).containsEntry("password", "admin".getBytes());
+    }
+
+    @Test
+    void deserializeWithUnstructured() throws JsonProcessingException {
+        Secret secret = Unstructured.OBJECT_MAPPER.readValue(testJsonString(), Secret.class);
+        assertThat(secret.getMetadata().getName()).isEqualTo("test-secret");
+        assertThat(secret.getType()).isEqualTo(Secret.SECRET_TYPE_OPAQUE);
+        assertThat(secret.getData()).containsEntry("password", "admin".getBytes());
+    }
+
+    @Test
+    void deserializeYamlWithStringData() throws JsonProcessingException {
+        String s = """
+            apiVersion: v1alpha1
+            kind: Secret
+            metadata:
+              name: secret-basic-auth
+            type: halo.run/basic-auth
+            stringData:
+              username: admin
+              password: t0p-Secret
+            """;
+        Secret secret = new YAMLMapper().readValue(s, Secret.class);
+        assertThat(secret.getMetadata().getName()).isEqualTo("secret-basic-auth");
+        assertThat(secret.getType()).isEqualTo("halo.run/basic-auth");
+        assertThat(secret.getStringData()).containsEntry("username", "admin");
+        assertThat(secret.getStringData()).containsEntry("password", "t0p-Secret");
+    }
+
+    private String testJsonString() {
+        return """
+            {
+                "apiVersion": "v1alpha1",
+                "kind": "Secret",
+                "metadata": {
+                    "name": "test-secret"
+                },
+                "type": "Opaque",
+                "data": {
+                    "password": "YWRtaW4="
+                }
+            }
+            """;
+    }
+}

application/src/main/java/run/halo/app/infra/SchemeInitializer.java

@@ -31,6 +31,7 @@ import run.halo.app.core.extension.content.Snapshot;
 import run.halo.app.core.extension.content.Tag;
 import run.halo.app.extension.ConfigMap;
 import run.halo.app.extension.SchemeManager;
+import run.halo.app.extension.Secret;
 import run.halo.app.plugin.extensionpoint.ExtensionDefinition;
 import run.halo.app.plugin.extensionpoint.ExtensionPointDefinition;
 import run.halo.app.search.extension.SearchEngine;
@@ -66,6 +67,7 @@ public class SchemeInitializer implements ApplicationListener<ApplicationStarted
         schemeManager.register(Setting.class);
         schemeManager.register(AnnotationSetting.class);
         schemeManager.register(ConfigMap.class);
+        schemeManager.register(Secret.class);
         schemeManager.register(Theme.class);
         schemeManager.register(Menu.class);
         schemeManager.register(MenuItem.class);