Gradle Convention plugin for WireMock extensions

[oleg-nenashev]

Proposal

The Gradle build flow for WireMock extensions is quite complicated, because we produce standalone JARs and expect releases to Maven Central with all signing complications. It would be awesome to have a convention plugin that simplifies the pipeline

Scope

• Create a new Convention Plugin and get it released
• Update https://github.com/wiremock/wiremock-extension-template to use the plugin
• Update a few extensions, especially https://github.com/wiremock/wiremock-state-extension we use as a reference
• Update documentation on https://github.com/wiremock/community/blob/main/infra/maven-central.md

If there are any existing implementations, prototypes, blogs or etc, let us know!

No response

Reference any relevant documentation, other materials or issues/pull requests that can be used for inspiration.

• https://docs.gradle.org/current/samples/sample_convention_plugins.html