Modernize classes to use Python 3 syntax

[Eric-Arellano]

Python 3 makes it repetitive to subclass object and to call the verbose form of super().

We use this script to update the codebase to use the simpler style, excluding the contrib.python.checks.checker package. The main part of this script is these two regex substitutions:

re.sub(r"super\([a-zA-Z]+, [a-z]+\)", "super()")
re.sub(r"class (?P<className>[a-zA-Z]*)\(object\):", r"class \g<className>:")

[Eric-Arellano]

This depends on #7934 to be merged for green CI.

Each commit may be independently reviewed.

[jsirois]

My review of cf1d38d was cursory, but the other commits definitely look good.

[Eric-Arellano]

My review of cf1d38d was cursory, but the other commits definitely look good.

I did a close review of it, which is what resulted in 0042167. Will likely closely review one more time before merging. Hoping CI will catch issues as well.

Thanks for the review!