Initial version

This release caches the following:

• Gradle dependencies (~/.gradle/caches/modules-2)
• Gradle local build cache (~/.gradle/caches/build-cache-1)
• Gradle generated jars (~/.gradle/caches/*.*/generated-gradle-jars)
• Maven local repository (~/.m2/repository)

The action implements incremental caching, so if you have lots of dependencies (e.g. 500MiB), then adding a new one (or bumping a version) would not result in re-upload of all the contents like actions/cache would do. gradle-cache-action would create a second layer with modified files only, so it will reduce the time to upload the cache, and it would reduce the space used.