Add fish catch tracking

[CarelessEsper]

Add tracking for number of each type of fish caught during fishing trip (clears when disembarked). This is useful in a multi-player crew when it's time to split catches at the end of a trip. Config option is set to Off by default so it doesn't introduce clutter.

[CarelessEsper]

Summary of the changes since original PR:

• Made the tracking a bit more robust so it properly saves the state between sessions (without client restart). This is important if someone who is riding on another player's boat disconnects or logs out and still needs to track their contributions.
• The fish catch infoboxes are now properly cleared if the player "Escapes" from the helm of a boat or leaves in another non-standard way.
• Added a "!caught" command which gives a readout of how many fish a player has caught during the trip, which is useful for confirming splits in groups. The command would need to be used while still on the boat because the counts get cleared when you disembark. Screenshot below.

@Maewi Let me know if you have any thoughts/questions about these proposed changes. Would love to see these included in a future update to the plugin. Also open to feedback if you have any concerns.