Automatically update player alias when RSN changes

[Trottero]

Currently whenever a player changes their name on OSRS they have to manually execute /setrsn in order to update their alias for the discord bot. With some modifications to the bots database model it should be possible to automatically propagate the OSRS name change to bots configuration as well.

I propose to, upon setting an alias, instead of resolving the player and storing just the username, to additionally also store their playerId. The bot would then whenever this discord user executes a command use the playerId instead of the registered username. This of course means that the downstream API's require support for playerId to be passed when looking up stats instead of the username. Further impact analysis is required.