Rename src dir instead of removing

[singhd789]

Describe your changes

Previously, the --force-checkout option removed the checkout script and src_dir that was already generated and re-created them. This did not mimic the current --force-checkout behavior in Bronx (which is also a bit more safe). If --force-checkout is used, the src_dir is renamed (in the same location) to src.[timestamp].

This was only done for bare-metal builds. THe container build doesn't need this as the src code is INSIDE the container.

• also changed os bits to Path

Issue ticket number and link (if applicable)

Fixes #844

Checklist before requesting a review

• I ran my code
• I tried to make my code readable
• I tried to comment my code
• I wrote a new test, if applicable
• I wrote new instructions/documentation, if applicable
• I ran pytest and inspected it's output
• I ran pylint and attempted to implement some of it's feedback
• No print statements; all user-facing info uses logging module

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 84.34%. Comparing base (dea2038) to head (52dd89c).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #848      +/-   ##
==========================================
+ Coverage   84.14%   84.34%   +0.20%     
==========================================
  Files          71       71              
  Lines        4975     4996      +21     
==========================================
+ Hits         4186     4214      +28     
+ Misses        789      782       -7     

Flag	Coverage Δ
unittests	84.34% <100.00%> (+0.20%)	⬆️

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Files with missing lines	Coverage Δ
fre/make/create_checkout_script.py	97.46% <100.00%> (+9.96%)	⬆️
fre/make/create_docker_script.py	100.00% <100.00%> (ø)
fre/make/run_fremake_script.py	97.95% <100.00%> (+0.81%)	⬆️

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