Implement Storage Extension

[duckontheweb]

Related Issue(s):

• Closes Implement Storage Extension #734

Description:

Implements the Storage Extension, including tests + docs.

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.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 99.31034% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.54%. Comparing base (ca49adb) to head (1a07149).
⚠️ Report is 700 commits behind head on main.

Files with missing lines	Patch %	Lines
pystac/extensions/storage.py	98.26%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #745      +/-   ##
==========================================
+ Coverage   94.42%   94.54%   +0.12%     
==========================================
  Files          77       79       +2     
  Lines       11312    11602     +290     
  Branches     1346     1369      +23     
==========================================
+ Hits        10681    10969     +288     
- Misses        453      455       +2     
  Partials      178      178              

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