add support for dumping command buffers to dot files

[bashbaug]

Description of Changes

Adds support for dumping the contents of a command buffer to a file when the command buffer is finalized. The command buffers are described using the DOT graph description language, which can be used by various tools and editor extensions to visualize the structure of a command buffer.

Testing Done

Tested by dumping command buffers for all of the command buffer and command buffer mutable dispatch CTS tests and verifying that they generate valid DOT files.