f-edit-mode-drop-zone -> dev

Summary

1. It is difficult for users to find the right drop zone when they drag properties or parents into the new/editable entity in edit mode. This MR introduces a visually highlighted drop zone.
2. The "Edit", "+", and "Delete" buttons are only appended to the entity when the user has the necessary permissions. Prior to this MR, any authenticated user saw these buttons, which is not very user-friendly, because when they tried to update/delete/insert something the only the server response would indicate that they are not allowed to execute the desired transaction.

Additionally to the drop zone and the permission things, this MR contains some more cosmetic changes.

• full-width text-areas in the edit mode
• the property values span the full-width when not in edit mode. prior to this mr there was some space reserved for the edit mode buttons (e.g. trash button). This now handled when the editing of an entity begins.
• When the page is rather empty, the footer moved to the middle of the page, leaving an ugly space between the footer and the bottom of the view port.

Test Environment

Manual testing: start any linkahead profile with this branch and edit something.

Check List for the Author

Please, prepare your MR for a review. Be sure to write a summary and a focus and create gitlab comments for the reviewer. They should guide the reviewer through the changes, explain your changes and also point out open questions. For further good practices have a look at our review guidelines

• All automated tests pass
• Reference related Issues
• Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there spezifications? Are they satisfied?

For further good practices have a look at our review guidelines.