Replace Read Only Editor role with ViewersCanEdit setting (#10166)

* removes readonly editor role

* adds viewersCanEdit setting

This enable you to allow viewers to edit/inspect
dashboards in grafana in their own browser without
allowing them to save dashboards

* remove read only editor option from all dropdowns

* migrates all read only viewers to viewers

* docs: replace readOnlyEditor with viewersCanEdit

docs/sources/http_api/auth.md

@@ -100,7 +100,7 @@ Authorization: Bearer eyJrIjoiT0tTcG1pUlY2RnVKZTFVaDFsNFZXdE9ZWmNrMkZYbk
 
 **Example Request**:
 
-```http
+```http
 DELETE /api/auth/keys/3 HTTP/1.1
 Accept: application/json
 Content-Type: application/json

docs/sources/installation/configuration.md

@@ -292,10 +292,14 @@ organization to be created for that new user.
 
 The role new users will be assigned for the main organization (if the
 above setting is set to true).  Defaults to `Viewer`, other valid
-options are `Admin` and `Editor` and `Read Only Editor`. e.g. :
+options are `Admin` and `Editor`. e.g. :
 
-`auto_assign_org_role = Read Only Editor`
+`auto_assign_org_role = Viewer`
 
+### viewers can edit
+
+Viewers can edit/inspect dashboard settings in the browser. But not save the dashboard.
+Defaults to `false`.
 
 <hr>