Save layer setting in the region map UI (#12956) (#13166)

Includes manual edits to resolve merge conflicts.

src/core_plugins/region_map/public/region_map_vis_params.html

@@ -15,9 +15,8 @@
         id="regionMap"
         class="kuiSelect kuiSideBarSelect"
         ng-model="vis.params.selectedLayer"
-        ng-options="layer.name for layer in vis.type.params.vectorLayers"
+        ng-options="layer.name for layer in collections.vectorLayers track by layer.url"
         ng-change="onLayerChange()"
-        ng-init="vis.params.selectedLayer=vis.type.params.vectorLayers[0]"
       ></select>
     </div>
   </div>
@@ -29,8 +28,7 @@
     <div class="kuiSideBarFormRow__control">
       <select id="joinField"
               ng-model="vis.params.selectedJoinField"
-              ng-options="field.description for field in vis.params.selectedLayer.fields"
-              ng-init="vis.params.selectedJoinField=vis.params.selectedLayer.fields[0]"
+              ng-options="field.description for field in vis.params.selectedLayer.fields track by field.name"
       >
         <option value=''>Select</option></select>
     </div>

src/core_plugins/region_map/public/region_map_vis_params.js

@@ -49,6 +49,7 @@ uiModules.get('kibana/region_map')
           $scope.vis.params.selectedJoinField = $scope.vis.params.selectedLayer.fields[0];
         }
 
+
       }
     };
   });