[REQ][Server-Java] Generate Gradle project

Is your feature request related to a problem? Please describe.

Generating a client using the java generator yields a project with both Maven and Gradle set up to build the project. Generating a server using e.g. the jaxrs-spec generator yields a project that only has Maven set up (no build.gradle or wrapper). The non-generated projects I work on use Gradle, so having to use Maven means an additional tool to maintain/install/learn about.

Describe the solution you'd like

The relevant Gradle files should also be generated, as in other generators (gradle wrapper, build.gradle, settings.gradle etc).

Describe alternatives you've considered

• Use Maven
• Store the relevant files and manually copy into the project post generation

Additional context

This seems commonplace in other generators, so plenty of precedent to work off.

Compare the Gradle files generated by the Java client generator with the jaxrs-spec server generator, focusing on the build.gradle, settings.gradle, and Gradle wrapper requested in the issue. Verify that a generated server project includes these files and can be built with Gradle, matching the existing Maven setup.