backups: Add support for project level backups

[nijel]

Proposed changes

Fixes #7066

Checklist

• [ ] Lint and unit tests pass locally with my changes.
• [ ] I have added tests that prove my fix is effective or that my feature works.
• [ ] I have added documentation to describe my feature.
• [ ] I have squashed my commits into logic units.
• [ ] I have described the changes in the commit messages.

Other information

[codecov[bot]]

Codecov Report

Merging #7922 (573fe88) into main (c8f5079) will not change coverage. The diff coverage is n/a.

:exclamation: Current head 573fe88 differs from pull request most recent head 1137beb. Consider uploading reports for the commit 1137beb to get more accurate results

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##             main    #7922   +/-   ##
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  Coverage   90.91%   90.91%           
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  Files         679      679           
  Lines       50555    50555           
  Branches     7807     7807           
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  Hits        45962    45962           
  Misses       3218     3218           
  Partials     1375     1375