ci: use latest actions/setup-java with actions/setup-gradle

[nschonni]

• there was a new distribution key required for the versions moving from v1
• pinned the version to the commit hash for security. Should be easy to be kept up-to-date with the separate PR that adds Dependabot
• hoist the actions/checkout before the java setup, so the gradle files are availble to figure out the cache key
• dropped the actions/cache setup, since it is built-in/bundled witht the actions/setup-java config. It did drop the .konan folders, but that could be added back as part of cache-dependency-path from https://github.com/actions/setup-java#inputs