feat: common websocket client

[PhilippHeuer]

Prerequisites for Code Changes

• This pull request follows the code style of the project
• I have tested this feature

Changes Proposed

This improves our testing capabilities in modules that use websocket connections.

• move common code into a websocket-client module
• chat now uses the websocket-client module
• pubSub now uses the websocket-client module
• adds getLatency to pubsub / pubsubpool
• adds a TestEventManager that tracks a list of all published events in order for testing
• uses the spec instead of the builder approach for the WebsocketConnection

and now we can:

• mock the websocket connection and validate that messages would be send as expected
• simulate messages from the websocket server

Additional Information

This also includes a few example tests for chat / pubSub to show how the usage would look like.

• https://github.com/twitch4j/twitch4j/blob/feature/websocket-common/pubsub/src/test/java/com/github/twitch4j/pubsub/TwitchPubSubTest.java
• https://github.com/twitch4j/twitch4j/blob/feature/websocket-common/chat/src/test/java/com/github/twitch4j/chat/TwitchChatTest.java
• https://github.com/twitch4j/twitch4j/blob/feature/websocket-common/chat/src/test/java/com/github/twitch4j/chat/TwitchChatRateLimitTest.java

[iProdigy]

Thanks for getting this off the ground!

[iProdigy]

Great work on this!