Implemented vkCmdUpdateBuffer and vkCmdFillBuffer.

Passes all tests in:
dEQP-VK.api.fill_and_update_buffer.*

Bug b/118619338 b/118383648

Change-Id: I3cf317b4cb766618a54b2550019ac2702c24bfed
Reviewed-on: https://swiftshader-review.googlesource.com/c/24529Tested-by: Alexis Hétu <sugoi@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>