[#25465] Support multi-select endpoint deletion and fixed a typo (backport #257)

[mergify]

Description

This PR improves endpoint management in the Qt UI by allowing multiple endpoints to be selected and removed in one action.

It also fixes the Delete Enpoint typo in the context menu label.

Local steps to test it

1. Single-click selects one endpoint row
2. Press keyboard key "Ctrl"/"Shift"
   2.1 Ctrl + click adds or removes individual rows from the selection
   2.2 Shift + click selects a contiguous row range
   2.3 Shift + <up/down> adds or removes individual adjacent row from the selection
3. Deletion
   3.1 Pressing Delete removes all selected endpoints
   3.2 Right-clicking a selected row keeps the current multi-selection

Documentation PR

@Mergifyio backport 3.2.x 2.14.x

Contributor Checklist

• Commit messages follow the project guidelines.

• Changes do not break current interoperability.

• New feature has been documented/Current behavior is correctly described in the documentation.

• Applicable backports have been included in the description.

Reviewer Checklist

• The PR has a milestone assigned.
• The title and description correctly express the PR's purpose.
• Check contributor checklist is correct.
• CI passes without warnings or errors.

---

This is an automatic backport of pull request #257 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of 2113d28 has failed:

On branch mergify/bp/2.14.x/pr-257
Your branch is up to date with 'origin/2.14.x'.

You are currently cherry-picking commit 2113d28.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   forms/mainwindow.ui
	modified:   src/qt/mainwindow.cpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   include/eprosimashapesdemo/qt/mainwindow.h

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[Danipiza]

Closing this PR as it is not required for backporting. The changes introduce a new feature that is intended to live only in the main branch and should not be included in stable/release branches