fix(notifications): optimise org notifications

[dtvillafana]

do not block main ui thread (use async)
implement caching for files (typically files do not change frequently)

Summary

This PR fixes the issue with the main thread blocking, and the UI freezing

Related Issues

Related #

Closes #
#1118

Changes

• adds caching for notifications
• batches files to be processed concurrently
• optimised early return for nodes that don't need to be processed

Checklist

I confirm that I have:

• Followed the
  Conventional Commits
  specification (e.g., feat: add new feature, fix: correct bug,
  docs: update documentation).
• My PR title also follows the conventional commits specification.
• Updated relevant documentation, if necessary.
• Thoroughly tested my changes.
• Added tests (if applicable) and verified existing tests pass with
  make test.
• Checked for breaking changes and documented them, if any.