drm/i915/gt: Include context status in debug dumps

This may be useful to identify contexts that are running even though
they are supposed to be closed or banned.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200610154046.22449-1-chris@chris-wilson.co.uk