Fix app crash when replacing views with object ref from `graph.findOrAddObject()`

[thinkh]

Fixes #402

Developer Checklist (Definition of Done)

• [x] Descriptive title for this pull request provided (will be used for release notes later)
• [x] All acceptance criteria from the issue are met
• [x] Branch is up-to-date with the branch to be merged with, i.e., develop
• [x] Code is cleaned up and formatted
• [x] Code documentation written
• [ ] Unit tests written
• [x] Tested in Chrome
• [ ] Tested in Firefox
• [x] Build is successful
• [x] Summary of changes written
• [ ] Wiki documentation written
• [x] Assign at least one reviewer
• [x] Assign at least one assignee
• [x] Add type label (e.g., bug, enhancement) to this pull request
• [x] Add next version label (e.g., next-version: minor) to this PR following semver

Summary of changes

• Fixes the missing object ref when replacing a view after adding and removing the view previously
  • The old object ref was reused when replacing the view, but got garbage collected
  • Using graph.findOrAddObject() fixes the object ref
  • See issue #402 for in-depth analysis and testing results.

Screenshots

[thinkh]

@rumersdorfer I've tested this PR with Ordino Public and it worked as before. However, it would be good to have a second opinion and testing cycle for Ordino. Please test Ordino Daily against a local Ordino instance with this PR. Check out the following branches in your local Ordino workspace:

Test if all actions regarding opening, closing and replacing a second view are still working as expected and if old provenance tracks (i.e., exported from Ordino Daily and imported locally) still result in the same state.

Please post your result here and if everything works submit a successful review. Let me know if you have further questions. Thanks.

[rumersdorfer]

@thinkh @oltionchampari Bug is fixed in Indications. 👍

[rumersdorfer]

Bug is also fixed in Ordino. 👍