drm/xe: Add plumbing for indirect context workarounds

Some upcoming workarounds need to be emitted from the indirect workaround
context so lets add some plumbing where they will be able to easily slot
in.

No functional changes for now since everything is still deactivated.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Bspec: 45954
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20250711160153.49833-7-tvrtko.ursulin@igalia.com


Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>