Texture dumping can already be done using VideoCommon's system (and in fact the same setting already enabled *both* of these). Dumping objects/TEV stages/texture fetches doesn't currently have an equivalent, but could be added to the FIFO player instead.

This moves much of the duplicated bounding box code into VideoCommon,
leaving only the specific buffer implementations in each backend.

The software backend doesn't actually use X11 in any capacity directly.

Continues the migration work started in 3a4c3bbe01e7a44ec997f4fbf0b678fba6f2d46c