v3dv/debug: add debug option to disable TFU codepaths

v3dv/debug: add debug option to disable TFU codepaths

This can have two main uses:
  * If we suspect a problem with TFU copies, we can disable it and
    check if other codepaths gets a test/app working.
  * To test other codepaths, as in general, TFU is the preferred
    option for copies.

Note that for now this is only for v3dv, as for v3d, mipmap generation
uses TFU without an alternative codepath.

With this option we also adds an assert if we try to submit a TFU job,
just in case we keep adding other methods that use TFU, and forget to
include the debug option there.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Reviewed-by: Juan A. Suarez <jasuarez@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21952>