Vulkan: Let BufferVk call into VMA for allocation when possible Previously BufferVk class maintains a DynamicBuffer pool per BufferVk object. This CL makes BufferVk skip DynamicBuffer pool in most cases and do its own BufferHelper allocation directly. DynamicBuffer pool is only used when desired, which is controled by a flag. With this CL, only UBO/SSBO/AtomicBuffer will still use DynamicBuffer pool if the buffer has to be allocated more than once. Bug: b/195588159 Change-Id: I3aa08cef10ee9ee9f01f16403c6fbb99b37f4a8a Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2901241 Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Tim Van Patten <timvp@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>