[WIP] Refactored webext-storage database close function

[lougeniaC64]

This is so not ready for primetime . . . enter at your own risk.

Pull Request checklist

• Breaking changes: This PR follows our breaking change policy
  • This PR follows the breaking change policy:
    • This PR has no breaking API changes, or
    • There are corresponding PRs for our consumer applications that resolve the breaking changes and have been approved
• Quality: This PR builds and tests run cleanly
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Branch builds: add [firefox-android: branch-name] to the PR title.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 49.15%. Comparing base (fd2bd27) to head (5c16c25).
Report is 7 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6424   +/-   ##
=======================================
  Coverage   49.15%   49.15%           
=======================================
  Files         147      147           
  Lines       13750    13750           
=======================================
  Hits         6759     6759           
  Misses       6991     6991           

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