Per-layer “attributes-only” mode in Editing plugin

[dominik-warch]

Some workflows require users to edit attributes while forbidding geometry changes. Right now, the Editing plugin exposes geometry tools whenever a layer is editable. The Attribute Table does not allow geometry editing but lacks the nice forms naturally.

A proposed solution would be to add a per-layer option to the Editing plugin to set an attributes-only mode. When enabled to specified layers:

• All geometry tools are hidden or disabled for that layer
• Edit dialogs/forms still allow attribute updates

{
   "name":"Editing",
   "cfg":{
     "snapping":true,
     "snappingActive":true,
     "layers": {
       "parcels": { "mode": "attributes-only" },
       "building": { "mode": "full" }
     },
     "defaultMode": "full"
   },
}

If mode or a layer itself is omitted, use the defaultMode, if defaultMode is not set, fall back to the full edit capabilities to remain backwards compatible.

[manisandro]

Another option would be to allow permitting the geometry like a regular attribute in the admin-gui.