Create app: RenderWithZones Manager

[AleziaKurdis]

This PR add the "RenderWithZones Manager" functionality to the Create App (Addressing Issue #795)

The "RenderWithZones Manager" can be called from the "Tools" menu of the "Entity list", applied on a selection of entities.

This open the "RenderWithZones Manager":

From the"RenderWithZones Manager" you will be able to visualize the different Visibility Zones used in that list of entities. You can use the "View" button to highlight the entities that will be visible from that zone. This can be helpful to make sure that no entities has been forgotten to be added to a visibility zone. (Trying to review that previously was demanding that you inspect the entities one by one. Just this justify that feature)

You can see if a Visibility Zones that is no more existing as an entity in order to "Remove" or "Replace" it on the listed entities.

You can also "Add" a new Visibility zone to a selection of entities among the listed one. and you can of course "Remove" or "Add" a Visibility Zone from a specific Entity.

The tool can operate automatically on locked entities (if you have permission) without have to unlock manually huge amount of entities.

The "RenderWithZones Manager" has also an "Undo" button to undo the last action performed.

PLEASE TEST CAREFULLY. If you think this too is missing something or if you have any suggestion let me know. Originally, I was to call it "Visibility Zones Manager" but I think it was more intuitive to reuse the property name for people to figure what it is.

As for the "Broken Url Report" the code has been all put in an isolated module. So easy to remove, and a minimum of mess.

[AleziaKurdis]

Add a warning when there are Visibility zone that are not identified. cause the related entity might simple not loaded if too far and small.

Also If we change the selection in the entity list (of create app) and call the "RWZ Manager" again, then the undo stack wasn't reset and might have become hazardous. This fixes also that.

[ksuprynowicz]

Thank you! This is seriously cool and will make setting up visibility zones much easier :) I tested it in desktop mode and works perfectly. Does it work in VR too? There's a popup about locked entities when removing entities from zone - how does it work in VR? Would it be possible to show that popup only when locked entities are selected? Right now it shows up also when everything is unlocked.