Cleaned up most warnings

[tristanpoland]

This pull request is primarily focused on code cleanup, removal of unused imports, and addition of #[allow(dead_code, unused_variables)] attributes to suppress compiler warnings. The most important changes are summarized below:

Code Cleanup and Simplification:

• Removed the definition of PLUGIN_API_VERSION in plugin_api/src/lib.rs as it was no longer needed.
• Removed the serve import from server/src/server/mod.rs as it was unused.

Suppression of Compiler Warnings:

• Added #[allow(dead_code, unused_variables)] attributes to several structs and functions in server/src/server/event_rep/structs.rs to suppress warnings about unused code. [1] [2] [3]
• Added #[allow(dead_code, unused_variables)] attributes to the HorizonServer and HorizonThread structs and their methods in server/src/server/mod.rs to suppress warnings about unused code. [1] [2] [3] [4] [5]

Removal of Unused Imports:

• Removed several unused imports from server/src/main.rs and server/src/server/config.rs to clean up the codebase. [1] [2]

Function Parameter Updates:

• Updated the new method in plugins/chronos_plugin/src/lib.rs and plugins/player_lib/src/lib.rs to use _plugins instead of plugins to indicate that the parameter is intentionally unused. [1] [2]
• Updated the setup_listeners function in plugins/player_lib/src/lib.rs to use _socket and _player instead of socket and player to indicate that the parameters are intentionally unused.