Add "invalid only" option to Reset panel

[focustense]

We have the option to reset NPC defaults/faces in the Maintenance tab, but now that additional checks are being added for missing plugins (i.e. face/default referencing a plugin that no longer exists), there is some likelihood of needing a large-scale but not full-scale "reset".

More specifically, if I've made direct changes to 500 NPCs, and then remove a fairly large mod like HPNPC or WICO or RS Children, that modified another 1500 NPCs, there's currently no way to fix everything for 1500 invalid entries without losing my 500 good ones.

With the detection in place, it would make sense to add an "Only invalid entries" checkbox to the Maintenance tab - or just a top level "Fix invalid" button - which does exactly this. Go through the list of NPCs, find any with temporary assignments due to missing plugins, and reset the default/face selections as needed, making these selections permanent (autosaved) and updating the mod selections to match.