drm/xe/lrc: Allow to add user commands mid context switch

Like done for post-context-restore commands, allow to add commands from
configfs in the middle of context restore. Since currently the indirect
ctx hardcodes the offset to CTX_INDIRECT_CTX_OFFSET_DEFAULT, this is
executed in the very beginning of engine context restore.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://lore.kernel.org/r/20250916-wa-bb-cmds-v5-6-306bddbc15da@intel.com


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