Adding gradle build file

[cjmang]

Adds a gradle build for the Java Client, with the intent to migrate from maven to gradle.

Also:

• Adds the ability to scout locations with hints
• Adds the ability to override the socket factory of the websocket (needed to fix an issue with StS)
• Makes the requestId generation be an incrementing AtomicInteger rather than a random integer. It's only used to identify requests sent to the server by this client.
• Fixed an issue where static AP event listener methods couldn't be registered.
• Adds a github action for publishing to maven central via jreleaser.