#2742 - Attachment point selection edition and deletion

[yuleicul]

Closes #2742

This PR has been divided into 5 small PRs in order to ease code reviews.
This PR can be merged after all 5 PRs are approved, and then the 5 small PRs will be closed.

• Part 1: Refactor #2742 [Part 1] Refactor R-Group attachment points as entities #2928
• Part 2: Selection #2742 [Part 2] Allow to hover on or select R-Group attachment points #2954
• Part 3: Deletion #2742 [Part 3] Allow removing R-Group Attachment Points using Erase Tool #2960
• Part 4: Bug fix #2742 [Part 4] Fix display of template and InfoPanel #2969
• Part 5: Edition #2742 [Part 5] Allow editing attachment points by context menu #2971

Check list

• unit-tests written
• e2e-tests written
• documentation updated
• PR name follows the pattern #1234 – issue name
• branch name doesn't contain '#'
• PR is linked with the issue
• base branch (master or release/xx) is correct
• task status changed to "Code review"

[rrodionov91]

Also please check how it works with this change #2977 .

[yuleicul]

@rrodionov91 really appreciate your detailed review!

[MartaWilliams]

Tests fail

ad. 3 - it's possible to remove the attachment point after selecting it and pressing Del hotkey or clicking the right mouse key, But after selecting the attachment and choosing Erase /scissors from the Top bar menu nothing is happening

ad.4 Editing existing attachments is not working - clicking the right mouse is giving only the "remove". According to AC should be possible to adit a type of attachment point (Choosing Primary/Secondary or both)