Make table extension columns serializable

[jsignell]

Related Issue(s): #872

Description:
The table extension was not serializable because the list of columns was not getting serialized properly. This PR takes inspiration from the original recommendation (thanks @martinfleis!) but pushes the change further back into the mixin class.

Note:
The _set_property functionality seems pretty useful overall and I was wondering if it should be use more thoroughly or if there is a reason not to use it.

PR Checklist:

• Code is formatted (run pre-commit run --all-files)
• Tests pass (run scripts/test)
• Documentation has been updated to reflect changes, if applicable
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[gadomski]

Agreed that the new functionality in the base class is useful; previous fixes (e.g.

pystac/pystac/extensions/raster.py

Lines 693 to 697 in 7819728

	@bands.setter
	def bands(self, v: Optional[List[RasterBand]]) -> None:
	self._set_property(
	BANDS_PROP, map_opt(lambda bands: [b.to_dict() for b in bands], v)
	)

) do the same thing, but at the extension level. IMO it'd be worth opening a new issue after this PR lands to convert any other extension-specific _set_property magic to use this new base-class functionality.

[codecov-commenter]

Codecov Report

Base: 90.06% // Head: 90.13% // Increases project coverage by +0.06% 🎉

Coverage data is based on head (e306f1c) compared to base (7819728).
Patch coverage: 75.00% of modified lines in pull request are covered.

📣 This organization is not using Codecov’s GitHub App Integration. We recommend you install it so Codecov can continue to function properly for your repositories. Learn more

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #992      +/-   ##
==========================================
+ Coverage   90.06%   90.13%   +0.06%     
==========================================
  Files          47       47              
  Lines        6161     6164       +3     
  Branches      917      920       +3     
==========================================
+ Hits         5549     5556       +7     
+ Misses        431      426       -5     
- Partials      181      182       +1     

Impacted Files	Coverage Δ
pystac/extensions/table.py	72.90% <66.66%> (+2.77%)	⬆️
pystac/extensions/base.py	93.65% <100.00%> (+0.20%)	⬆️

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report at Codecov.
📢 Do you have feedback about the report comment? Let us know in this issue.