[rich_utils] added Paragraph Help Formatters based on rich_argparse classes

[neoniobium]

This PR added two new argparse Formatter classes based on the equivalent classes in the rich_argparse package.

Since the ExtendedParagraphRichHelpFormatter was added in rich_argparse version 1.8.0 also bump the minimum version to 1.8.0.

Reference:

• Multi-line help text without empty linefeeds hamdanal/rich-argparse#180

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.52%. Comparing base (5e2b4ac) to head (87666e9).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1656      +/-   ##
==========================================
+ Coverage   99.50%   99.52%   +0.02%     
==========================================
  Files          21       21              
  Lines        4813     4816       +3     
==========================================
+ Hits         4789     4793       +4     
+ Misses         24       23       -1     

Flag	Coverage Δ
unittests	99.52% <100.00%> (+0.02%)	⬆️

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[kmvanbrunt]

Thanks for the PR, but I purposely don't include the non-standard help formatters from rich-argparse. As that list grows, I don't want the maintenance and support burden to keep track of them. If a cmd2 developer wants to use them in their application, it's trivial.

class ParagraphCmd2HelpFormatter(
    ParagraphRichHelpFormatter,
    Cmd2HelpFormatter,
):