run_code_generation.py updated comments with 2019 to 2020.
Put all date updates into this one CL.
This also updated hashes.

Bug: angleproject:4262
Change-Id: Ia213dd5e47f155986cbb4161d777724355878af0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1986994
Commit-Queue: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>