drm/tests: Add test cases for drm_rect_rotate()

Insert a parameterized test for the drm_rect_rotate() to ensure
correctness and prevent future regressions.

All possible rotation modes are covered by the test.

Signed-off-by: Arthur Grillo <arthurgrillo@riseup.net>
Reviewed-by: Maíra Canal <mcanal@igalia.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20230418230146.461129-5-arthurgrillo@riseup.net