Draft: Unavailable mod cleanup

The following mods have been removed from Nexus with no mirror available:

• [assets-textures/concept-art-vivec-face-replacement] removed
• [creatures-misc/golden-saint-variety] removed
• [gameplay-weapons/weapon-sheathing-tr] merged into [landmasses/tamriel-data]
• [assets-meshes/practical-pauldrons] removed due to outstanding issues

Closes #351 #352 #354 #358 #360 #361 #654

Only providing simple deletion of affected mods at the moment. Seeking feedback for a more graceful way to implement this. (If possible)