surface: fix damage transformation

Closes #3194 (closed)

This MR fixes surface-to-buffer and vice versa damage transformation, making it equal with Weston and KWin behavior.

• weston-simple-damage now works correctly with and without --use-viewport, with any transform and scale.
• weston-simple-damage --rotating-transform, however, doesn't work correctly. Removing wlr_client_buffer_apply_damage() call fixes the problem. Not sure what causes this; Mutter seems to have a similar issue.
• Firefox 92+ with WebRender compositor enabled still has minor damage issues, related to subsurface position changing. This is caused by modifying buffer_damage on subsurface motion and then transforming the resulting damage in wlr_surface_get_effective_damage() (Firefox subsurfaces have WL_OUTPUT_TRANSFORM_FLIPPED_180 buffer transform).