Notify the user when deleting a superproject

[humitos]

Now, when the user deletes a superproject (a Project that has subproject(s)) that Project is deleted but all the subprojects are "disconnected" from its parent and now become just regular Project (change the hierarchy from sub to project).

This means that the URL for those subproject changes also and probably other things are changed also.

We need to find a good pattern to handle this in a better way, but our first step will be to alert the user that this will happen when they try to delete the superproject.

The flow should be:

1. user tries to remove the superproject
2. user is informed in a very well detailed way what will happen and how the subprojects will be affected
3. user accepts it
4. project is deleted

For this issue we need:

• know exactly what is happening now when a superproject is deleted
• write a good message to communicate this to the user
• implement the flow proposed in this issue
• write some tests for this flow

Ref: #3649

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.