Need test for `gfx_GetClipRegion`

[ZERICO2005]

We need tests for bool gfx_GetClipRegion(gfx_region_t *region)

If you need help or clarification on what gfx_GetClipRegion does, you can ping one of the developers in https://discord.gg/5yVK3UjcX7 or ask a question in this github issue.

TODO:

• test cases where no clipping
• test cases where clipping is performed on one side, and on multiple sides
• test cases where the region is outside the clipping area
• test cases where the clipping region has zero-width or zero-height
• test gfx_GetClipRegion after setting new screen clipping regions with gfx_SetClipRegion