Vulkan: Clean up submitFrame/submitCommands ContextVK has two functions, submitFrame, and submitCommands. ContextVk::SubmitFrame means to be frame boundary or FBO boundary, usually refers to submission triggered by API, for example, glFlush/glFinish or FBO switches. ContextVk::submitCommands was added later to mean any kind of submission. It could be triggered by internal logic, for example, when we think we have accumulated too much staged updates. The odd thing is that ContextVk::submitFrame calls ContextVk::submitCommands, which calls RendererVk::submitFrame. I believe this is because when we introduced ContextVk::submitCommands, we did not bother rename RendererVk's API. This CL renames RendererVk::submitFrame and CommandQueue::submitFrame and CommandProcessor::submitFrame to submitCommands to be consistent with ContextVk's function names. This CL also removes unused function ContextVk::isSerialInUse() This CL also removes unnecessary vk:: namespace in CommandProcessor Bug: b/259148812 Change-Id: If074e381168950143ad56a728f23caa298e5f355 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4027284 Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org> Commit-Queue: Charlie Lao <cclao@google.com> Reviewed-by: Yuxin Hu <yuxinhu@google.com>