gallium/tools: update trace scripts to Python 3
Bring the scripts for parsing, dumping state and diffing of Gallium trace files to modern day by updating them to Python 3.
Add option '-p' to some tools for outputting only plaintext instead of ANSI / colorized format.
Also fix state parsing of some dumps by adding 'clear_render_target' and 'get_disk_shader_cache' to ignored calls list.
Closes: #4321 (closed) Signed-off-by: Matti Hamalainen ccr@tnsp.org