Reverts "[Impeller] Add interface for submitting multiple command buffers at once."

[auto-submit]

Reverts #50139
Initiated by: jonahwilliams
This change reverts the following previous change:
Original Description:
The Impeller Vulkan backend benefits from batching submission to the vk graphics queue. Managing this automatically is non-trivial and adds surprising/fragile thread based behavior, see: #49870

Instead, introduce an impeller::CommandQueue object that command buffers must be submitted to in lieu of CommandBuffer->Submit, which has been made private.

TLDR

old

buffer->Submit();

new

context.GetQueue()->Submit({buffer});

The Metal and GLES implementations internally just call the private CommandBuffer->Submit, though there may be future opportunities to simplify here. The Vulkan implementation is where the meat is.

Aiks takes advantage of this by storing all command buffers on the aiks context while rendering a frame, and then performing one submit in aiks_context render. I don't think this will introduce any thread safety problems, as we don't guarantee much about aiks context - nor do we use it in a multithreaded context as far as I know.

Other tasks such as image upload still just directly submit their command buffers via the queue.

Fixes flutter/flutter#141123