Validate stride when using clut, more reporting.
Centralize render-to-tex logic, support mirrors.

Now everything is decided in AttachFramebuffer().
Report decoding a texture from a VRAM mirror.

Might mainly be depth textures?
Log more info about skipped subarea renders.
Skip memcpy fb download when already downloaded.

Fixes Final Fantasy Tactics lag, discussion in #6308.
Merge pull request #6320 from unknownbrackets/texcache

Validate render to texture better, report more, and support vram mirrors