Remove mixin config references upon mixin removal

[FamroFexl]

Minecraft Development for IntelliJ plugin version

2024.2-1.8.2

Description of the feature request

When deleting Mixins java files that are deprecated, defunct, or used for debugging purposes, it would be convenient if they were automatically removed from the appropriate mixin configs (modid.mixins.json, modid-client.mixins.json) as well.