feat: plugin configs

[zorbyte]

When creating a plugin, one of the fields that can be provided in the config is an associated entity for TypeORM.
Instead of having monolithic entities which encapsulate entire guild and user configs, configs will be on a per plugin basis,
and share in common only the various types of snowflakes (user, channel, guild etc.).

Public interfaces for the database which other plugins can also access would be read only and would be part of the plugin class definition.

Local functions for db access that read, write and delete should be their own utility, likely a custom repository.