venus: support caching common buffer requirements for async buffer creation
The 1st commit fixes a tiny bug.
The 2~6 commits are just tiny and good-to-have refactorings.
The 7th commit implements the entire buffer cache flows with some empty stub apis to leave the path disabled.
The 8~10 commits implement the stub apis added in the 7th commit and enable the async buffer creation path for cached entries.
TEST: Vulkan game titles on Android no longer make synchronous buffer creation or memory requirement query calls at runtime.
TEST: dEQP-VK.api.buffer.* and dEQP-VK.api.buffer_view.* pass on ANV and RADV