Merge acme4j-utils into acme4j-client

The separation of acme4j-client and acme4j-utils was a design decision
that should avoid BouncyCastle to be a hard dependency of acme4j-client.
Anyhow acme4j is not really usable without BouncyCastle, so acme4j-utils
is used in almost all projects anyway.

This merge allows to extend the client API with some nice methods that
will make it easier to use.

acme4j-smime/pom.xml

@@ -34,11 +34,6 @@
             <artifactId>acme4j-client</artifactId>
             <version>${project.version}</version>
         </dependency>
-        <dependency>
-            <groupId>org.shredzone.acme4j</groupId>
-            <artifactId>acme4j-utils</artifactId>
-            <version>${project.version}</version>
-        </dependency>
         <dependency>
             <groupId>org.bouncycastle</groupId>
             <artifactId>bcprov-jdk18on</artifactId>

acme4j-smime/src/main/java/module-info.java

@@ -17,7 +17,6 @@
  */
 module org.shredzone.acme4j.smime {
     requires org.shredzone.acme4j;
-    requires org.shredzone.acme4j.utils;
 
     requires transitive jakarta.mail;
     requires static com.github.spotbugs.annotations;