ANGLE translator's parser code generation is changed to use the binaries
of flex/bison stored in the cloud.  scripts/run_code_generation.py now
automatically runs these files if the input files change.

Bug: angleproject:3419
Change-Id: Icce4247f93b27baf8ee12dbb16112fa2cc98c111
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1940572Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>