Add support for output files when auto-generating configurations

[desilinguist]

As #598 states, changes to the prompt_toolkit library prevent auto-generated configuration files(both interactive and batch) from being redirected to files.

This PR:

• Adds the --output or -o option when generating configuration files.
  • If not specified, configs are printed to screen just like before.
  • Interactive messages show the name of the output file being written to.
• Updated documentation text and images to demonstrate the new --output option.
• Add new tests for --output option to test_cli.py.
• Refactor test_utils.TestSetupRsmCmdParser to add support for --output option and to use test generators instead of individual functions.
• Fix buggy rsmexplain unit test and test data file.

To review this

• Check out and install this branch into your environment. Run the <tool> generate --output <file> or <tool> generate --interactive --output <file> commands with various other options (--subgroups, --quiet, etc.) to check that everything works as expected.
• Confirm that the documentation looks okay.

Closes #598

[codecov]

Codecov Report

Patch coverage: 94.44% and project coverage change: -0.03% ⚠️

Comparison is base (9e0343c) 95.82% compared to head (552327e) 95.80%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #640      +/-   ##
==========================================
- Coverage   95.82%   95.80%   -0.03%     
==========================================
  Files          32       32              
  Lines        4430     4432       +2     
==========================================
+ Hits         4245     4246       +1     
- Misses        185      186       +1     

Files Changed	Coverage Δ
rsmtool/utils/commandline.py	96.76% <75.00%> (-0.38%)	⬇️
rsmtool/rsmcompare.py	95.00% <100.00%> (ø)
rsmtool/rsmeval.py	97.89% <100.00%> (ø)
rsmtool/rsmexplain.py	92.15% <100.00%> (-0.04%)	⬇️
rsmtool/rsmpredict.py	99.35% <100.00%> (ø)
rsmtool/rsmsummarize.py	97.84% <100.00%> (ø)
rsmtool/rsmtool.py	99.21% <100.00%> (ø)
rsmtool/rsmxval.py	98.18% <100.00%> (ø)

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[tamarl08]

Looks good!

[damien2012eng]

Works great!