raise TypeError if input is not list of str for convert_list_to_comma_separated_string converter

[vnktshr21]

• 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?

convert_list_to_comma_separated_string converter now checks if the input is a list of str and raise a TypeError if its not, so that we do not accidentally take in any other type of input and do a join on that in case of writeable attributes using this type.

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

convert_list_to_comma_separated_string was assuming a list input, which could be wrong.

What testing has been done?

Add a nifake unit test to confirm that TypeError is thrown.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.08%. Comparing base (442e169) to head (6cf9c8c).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2154   +/-   ##
=======================================
  Coverage   90.07%   90.08%           
=======================================
  Files          71       71           
  Lines       18664    18666    +2     
=======================================
+ Hits        16812    16815    +3     
+ Misses       1852     1851    -1     

Flag	Coverage Δ
codegenunittests	84.44% <ø> (ø)
nidcpowersystemtests	94.65% <ø> (+0.04%)	⬆️
nidcpowerunittests	89.53% <ø> (ø)
nidigitalsystemtests	92.26% <ø> (ø)
nidigitalunittests	68.44% <ø> (ø)
nidmmsystemtests	92.72% <ø> (ø)
nifakeunittests	85.51% <100.00%> (+0.02%)	⬆️
nifgensystemtests	94.61% <ø> (ø)
nimodinstsystemtests	73.85% <ø> (ø)
nimodinstunittests	94.20% <ø> (ø)
nirfsgsystemtests	82.40% <ø> (ø)
niscopesystemtests	92.94% <ø> (ø)
niscopeunittests	43.20% <ø> (ø)
nisesystemtests	91.50% <ø> (ø)
niswitchsystemtests	82.03% <ø> (ø)
nitclksystemtests	94.87% <ø> (ø)
nitclkunittests	98.26% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
generated/nifake/nifake/_converters.py	95.65% <100.00%> (+0.06%)	⬆️

... and 2 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 442e169...6cf9c8c. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.