Reverts "[Impeller] Encode directly to command buffer for Vulkan."

[auto-submit]

Reverts #49780
Initiated by: jonahwilliams
This change reverts the following previous change:
Original Description:
Part of flutter/flutter#140804

Rather than using impeller::Command, the impeller::RenderPass records most state directly into the Vulkan command buffer. This should remove allocation/free overhead of the intermediary structures and make further improvements to the backend even easier. This required a number of other changes to the renderer:

1. The render pass holds a strong ptr to the context. This helps avoid locking continually while encoding, which is quite slow.
2. barriers need to be encoded on the producing side, and not the consuming side. This is because we'll actually run the consuming code before the producing code. i.e. we transition to shader read at the end of a render pass instead of when binding.
3. I've updated the binding code to also provide the descriptor type so that we don't need to look it up from the desc. set.
4. I added a test render pass class that records commands.