Adds the remaining widget docstrings

[MarcSkovMadsen]

Adds the remaining widget docstrings and also docstrings to the panel and widgets modules.

The purpose is to make it much easier to navigate the code in a modern IDE like VS Code or PyCharm

[MarcSkovMadsen]

Why do you add the noqa below @philippjfr?

I have a feeling it is what hinders tooltips for pn.widgets to show up in VS Code??

[codecov]

Codecov Report

Merging #3367 (e87d1ee) into master (3504e87) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3367      +/-   ##
==========================================
+ Coverage   83.33%   83.34%   +0.01%     
==========================================
  Files         198      198              
  Lines       26791    26791              
==========================================
+ Hits        22327    22330       +3     
+ Misses       4464     4461       -3     

Impacted Files	Coverage Δ
panel/__init__.py	100.00% <ø> (ø)
panel/widgets/__init__.py	100.00% <ø> (ø)
panel/widgets/speech_to_text.py	78.76% <ø> (ø)
panel/widgets/tables.py	88.20% <ø> (ø)
panel/widgets/terminal.py	72.03% <ø> (ø)
panel/widgets/text_to_speech.py	85.18% <ø> (ø)
panel/widgets/texteditor.py	100.00% <ø> (ø)
panel/io/server.py	78.30% <0.00%> (+0.21%)	⬆️
panel/io/reload.py	71.73% <0.00%> (+2.17%)	⬆️

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[jbednar]

Usuallynoqa will be added if we have an import provided for API purposes, to avoid having linters complain about unused imports.