Persist dirty state of string widget #11092

[chiatt]

Types of changes

• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Description of Change

Persists unsaved value in widget if a user switches between cards in the card tree.

Issues Solved

Closes #11092

Checklist

• I targeted one of these branches:
  • [x] dev/7.6.x (under development): features, bugfixes not covered below
  • [ ] dev/7.5.x (main support): regressions, crashing bugs, security issues, major bugs in new features
  • [ ] dev/6.2.x (extended support): major security issues, data loss issues
• [x] I added a changelog in arches/releases
• [ ] I submitted a PR to arches-docs (if appropriate)
• [x] Unit tests pass locally with my changes
• [ ] I added tests that prove my fix is effective or that my feature works
• [ ] My test fails on the target branch