fix: re-apply windows hover preview image fix & improve hover preview performance

[SeriousBug]

Pull Request Checklist

This PR:

• Re-applies the hover preview Windows image fix that was reverted here: 7890c01
• Extends the /notes/render engine API to allow overriding the destination and flavor, then moves the hover preview rendering to the engine
• Removes most MDUtilsV4 usages from note reference rendering, improves performance by avoiding some unnecessary processor cloning and avoiding re-parsing the referenced region.
• Some tests have been cleaned up to not use MDUtilsV4.

I was originally attempting to remove all MDUtilsV4 usages from note reference rendering, but this was causing errors with some tests. The issue was MDUtilsV4 usages in tests, but fixing those required even more fixes everywhere else. I managed to fix some, but eventually gave up and reintroduced the compatibility back into note reference rendering.

Testing

• Write Tests
• Confirm existing tests pass
• Confirm manual testing
• If your tests changes an existing snapshot, make sure that snapshots are updated
• If you are adding a new language feature (graphically visible in VS Code/preview/publishing), make sure that it is included in the test workspace

Docs

• if your change reflects documentation changes, also submit a PR to dendron-site and mention the doc PR link in your current PR

Analytics

• if you are adding analytics related changes, make sure the Telemetry docs are updated

[kevinslin]

super excited about these changes :)