Vulkan: Cleanup shared ring buffer cmd alloc feature. Changes: - Simplified "SharedCommandBlockPool" interface. Removed "ptrOut" and "usesCommandHeaderSizeForOffsetOut" parameters, because "headerOut" has exactly the same value. - Refactoring of "SharedCommandBlockPool" classes. Some public methods made private, inline, or moved into ".cpp". - Replace some getters with more specific/restrictive methods: - "RingBufferAllocatorBuffer::getStorageSize()" -> "isEmpty()" - "CommandBufferHelperCommon::getAllocator()" -> "hasAllocatorLinks()" - Added extra ASSERT()s. - fixed typo "kMinRingBufferAllocatio(r)Capacity" - other minor modifications. Bug: angleproject:6401 Bug: b/256666069 Change-Id: I8f5c1c928bac5f8ecdfce7d411834f7ea39d11ac Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4218364 Commit-Queue: Igor Nazarov <i.nazarov@samsung.com> Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Charlie Lao <cclao@google.com> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>