feat: allow custom websocket close delay

[iProdigy]

Prerequisites for Code Changes

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

Issues Fixed

• Allows for faster underlying socket close for applications where this is required (e.g., minecraft plugins on disable, which triggers class unloading)

Changes Proposed

• Add closeDelay to WebsocketConnectionConfig
• Don't return from WebsocketConnection#close until the underlying Socket has fully closed

Additional Information

nv-websocket-client defaults closeDelay to 10_000 - this seems high to just wait for a single frame, so we default to 1000 instead (this part of the websocket protocol is just good manners anyway, so it's not the end of the world if formal close isn't received)