tu: VK_EXT_conditional_rendering

This isn't exposed by the blob driver, but since the draw skipping is implemented entirely by the SQE firmware, I was able to reverse-engineer the relevant packets. It's based on top of !6007 (merged), both because it depends on c2b2216b in the other series and because the CTS tests use VK_KHR_draw_indirect_count without checking first (whoops!). f03ef72d is cherry-picked from !5720 (merged), as it turns out this fix is needed for tests for both features.