Run flake8 on examples and system_tests

[texasaggie97-zz]

• This contribution adheres to CONTRIBUTING.md.
• I've updated CHANGELOG.md if applicable.
• I've added tests applicable for this pull request

What does this Pull Request accomplish?

• When we quit copying examples and system_tests to generated, we no longer had flake8 coverage of these folders
• Run flake8 on system_tests and examples for each driver

List issues fixed by this Pull Request below, if any.

What testing has been done?

• flake8

[marcoskirsch]

It's really obnoxious that we need to unroll the same thing for each module... twice!

[codecov]

Codecov Report

Merging #1283 into master will decrease coverage by 5.43%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1283      +/-   ##
==========================================
- Coverage   91.69%   86.25%   -5.44%     
==========================================
  Files          20       18       -2     
  Lines        3695     4162     +467     
==========================================
+ Hits         3388     3590     +202     
- Misses        307      572     +265     

Flag	Coverage Δ
#codegenunittests	?
#nidcpowersystemtests	98.58% <ø> (?)
#nidigitalsystemtests	51.72% <ø> (?)
#nidmmsystemtests	95.48% <ø> (?)
#nifakeunittests	95.90% <ø> (-0.20%)	⬇️
#nimodinstsystemtests	87.23% <ø> (?)
#nimodinstunittests	95.83% <ø> (-0.18%)	⬇️
#niscopesystemtests	83.15% <ø> (?)
#nisesystemtests	100.00% <ø> (?)
#nitclksystemtests	100.00% <ø> (?)
#nitclkunittests	95.78% <ø> (+0.03%)	⬆️

Impacted Files	Coverage Δ
generated/nitclk/nitclk/session.py	95.45% <0.00%> (-2.06%)	⬇️
generated/nifake/nifake/session.py	97.74% <0.00%> (ø)	⬆️
generated/nifake/nifake/_converters.py	96.59% <0.00%> (ø)	⬆️
build/helper/documentation_helper.py
build/helper/parameter_usage_options.py
build/helper/metadata_find.py
build/helper/documentation_snippets.py
build/helper/__init__.py
build/helper/metadata_add_all.py
build/helper/metadata_merge_dicts.py
... and 11 more

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