feat(ui-plugin-bundler-kit): support function-based configuration for env-aware builds (#7572)

#### What type of PR is this?

/area ui
/area plugin
/kind improvement
/milestone 2.21.x

#### What this PR does / why we need it:

rsbuild example:

```ts
export default rsbuildConfig({
  rsbuild: ({ env, envMode }) => {
    console.log(env,envMode);

    return {
      resolve: {
        alias: {
          "@": "./src",
        },
      },
      plugins: [pluginSass()],
    };
  },
});
```

```ts
export default viteConfig({
  vite: ({ mode }) => {
    const env = loadEnv(mode, process.cwd(), '');
    console.log(env);
    return {
      resolve: {
        alias: {
          "@": fileURLToPath(new URL("./src", import.meta.url)),
        },
      },
    };
  },
});
```

#### Does this PR introduce a user-facing change?

```release-note
None
```

ui/packages/ui-plugin-bundler-kit/README.md

@@ -114,7 +114,7 @@ interface ViteUserConfig {
   /**
    * Custom Vite configuration
    */
-  vite: UserConfig;
+  vite: UserConfig | UserConfigFnObject;
 }
 ```
 
@@ -131,7 +131,7 @@ interface RsBuildUserConfig {
   /**
    * Custom Rsbuild configuration
    */
-  rsbuild: RsbuildConfig;
+  rsbuild: RsbuildConfig | ((env: ConfigParams) => RsbuildConfig);
 }
 ```
 

ui/packages/ui-plugin-bundler-kit/src/rsbuild.ts

@@ -3,6 +3,7 @@ import {
   mergeRsbuildConfig,
   type RsbuildConfig,
   type RsbuildMode,
+  type ConfigParams,
 } from "@rsbuild/core";
 import { getHaloPluginManifest } from "./utils/halo-plugin";
 import { DEFAULT_OUT_DIR_DEV, DEFAULT_OUT_DIR_PROD } from "./constants/build";
@@ -21,7 +22,7 @@ export interface RsBuildUserConfig {
   /**
    * Custom Rsbuild config.
    */
-  rsbuild: RsbuildConfig;
+  rsbuild: RsbuildConfig | ((env: ConfigParams) => RsbuildConfig);
 }
 
 function createRsbuildPresetsConfig(manifestPath: string) {
@@ -134,6 +135,10 @@ export function rsbuildConfig(config?: RsBuildUserConfig) {
   );
   return defineConfig((env) => {
     const presetsConfig = presetsConfigFn(env);
-    return mergeRsbuildConfig(presetsConfig, config?.rsbuild || {});
+    const userConfig =
+      typeof config?.rsbuild === "function"
+        ? config.rsbuild(env)
+        : config?.rsbuild || {};
+    return mergeRsbuildConfig(presetsConfig, userConfig);
   });
 }

ui/packages/ui-plugin-bundler-kit/src/vite.ts

@@ -1,4 +1,9 @@
-import { defineConfig, mergeConfig, UserConfig } from "vite";
+import {
+  defineConfig,
+  mergeConfig,
+  UserConfig,
+  UserConfigFnObject,
+} from "vite";
 import Vue from "@vitejs/plugin-vue";
 import { EXTERNALS, GLOBALS } from "./constants/externals";
 import { DEFAULT_OUT_DIR_DEV, DEFAULT_OUT_DIR_PROD } from "./constants/build";
@@ -16,7 +21,7 @@ export interface ViteUserConfig {
   /**
    * Custom Vite config.
    */
-  vite: UserConfig;
+  vite: UserConfig | UserConfigFnObject;
 }
 
 function createVitePresetsConfig(manifestPath: string) {
@@ -72,6 +77,10 @@ export function viteConfig(config?: ViteUserConfig) {
   );
   return defineConfig((env) => {
     const presetsConfig = presetsConfigFn(env);
-    return mergeConfig(presetsConfig, config?.vite || {});
+    const userConfig =
+      typeof config?.vite === "function"
+        ? config.vite(env)
+        : config?.vite || {};
+    return mergeConfig(presetsConfig, userConfig);
   });
 }