fix: speed up void db migration

[hanabi1224]

Summary of changes

Changes introduced in this pull request:

• hard link files recursively instead of copying in void db migration to speed up the process and reduce additional disk usage

Reference issue to close (if applicable)

Closes #5451

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

[LesnyRumcajs]

If there are no caveats, I'd choose a rename instead of a hardlink. It's just simpler. The implementation will perhaps require more work, but we should strive to make Forest simpler and, in turn, more maintainable. Lingering hard links won't help in that.

[hanabi1224]

If there are no caveats, I'd choose a rename instead of a hardlink. It's just simpler. The implementation will perhaps require more work, but we should strive to make Forest simpler and, in turn, more maintainable. Lingering hard links won't help in that.

@LesnyRumcajs Done

[LesnyRumcajs]

Might be worth adding to the changelog, given it massively speeds up db migrations on some systems.

[hanabi1224]

Might be worth adding to the changelog, given it massively speeds up db migrations on some systems.

@LesnyRumcajs changelog updated, please re-approve.