Removes the custom logger class and uses the python logging class.
Moves the argument descriptions into argparse help.
Keep build directories around by default. Essential for normal use.
Print more debug messages.

Bug: angleproject:5133
Change-Id: Ida48828512abe60ee7d16873cbdb87c58529a60a
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2446898
Commit-Queue: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>