[REQ] Conveniently only generate client classes

I often generate client code from a spec file with the maven plugin, like this:

        <configuration>
          <inputSpec>src/main/oas/oas.yaml</inputSpec>

          <generatorName>java</generatorName>
          <library>native</library>

          <configOptions>
            <dateLibrary>java8</dateLibrary>
          </configOptions>

          <apiPackage>${project.groupId}.client</apiPackage>
          <modelPackage>${project.groupId}.client</modelPackage>
          <invokerPackage>${project.groupId}.client</invokerPackage>

          <generateApiTests>false</generateApiTests>
          <generateModelTests>false</generateModelTests>
          <generateModelDocumentation>false</generateModelDocumentation>
          <generateApiDocumentation>false</generateApiDocumentation>
          <supportingFilesToGenerate>
            ApiException.java,Pair.java,ApiClient.java
          </supportingFilesToGenerate>
        </configuration>

It would be nice to have a single config property that disables the generation of tests, documentation and also all the supporting files that are not needed for compilation.

It would also be nice to be able to specify the package name only once if you want everything in the same package. packageName does not do this.

Start with the Maven plugin configuration and the existing generateApiTests, generateModelTests, generateModelDocumentation, generateApiDocumentation, supportingFilesToGenerate, and package settings shown in the issue. Trace how these options are applied, then define and test the requested consolidated generation and package-name behavior against the Java client example.