lavapipe: Switch to the common sync framework
The common Vulkan sync framework will do most of the queueing for us. It will even sort out timeline semaphore dependencies and ensure everything executes in-order. All we have to do is make sure our vk_sync type implements VK_SYNC_FEATURE_WAIT_PENDING. This lets us get rid of a big pile of code.
This depends on !15566 (merged)