drm/xe/kunit: Add basic tests for GuC context ID Manager

Before we switch-over submission code to use new GuC context ID
Manager, lets add some kunit tests to make sure that ID manager
works as expected.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240313221112.1089-4-michal.wajdeczko@intel.com