Migrate QESD spatial customisations (#267)

* [SUPDESQ-135]
- Migrated QESD customisations from forked repo ckan-spatial
- Refactored spatial customisations into their own spatial folder for templates and webassets

* Added check and warning message if dataset identifier does not exist

ckanext/qdes_schema/fanstatic/spatial/spatial_map_input.css

@@ -0,0 +1,77 @@
+#spatial-map-input #spatial-map-input-container {
+  height: 400px;
+  width: 100%;
+  margin-bottom: 30px;
+}
+
+@media (min-width: 768px){
+  #spatial-map-input #spatial-map-input-container {
+    height: 600px;
+  }
+}
+
+.leaflet-control-arrow{
+  border: none;
+  box-shadow: none;
+  padding: 3px;
+}
+.leaflet-control-arrow-left,
+.leaflet-control-arrow-right,
+.leaflet-control-arrow-up,
+.leaflet-control-arrow-down{
+  width: 22px;
+  height: 22px;
+  border-radius: 4px;
+  display: block;
+  border: 1px solid #aaa;
+  font-size: 15px;
+  text-align: center;
+  position: relative;
+}
+.leaflet-control-arrow-left{
+  left: -12px;
+  float: left;
+}
+.leaflet-control-arrow-right{
+  right: 12px;
+  float: right;
+}
+.leaflet-control-arrow-down{
+  clear: both;
+}
+.leaflet-control-arrow-left:before,
+.leaflet-control-arrow-right:before,
+.leaflet-control-arrow-up:before,
+.leaflet-control-arrow-down:before{
+  color: #000;
+  font-family: "FontAwesome";
+}
+.leaflet-control-arrow-left:hover:before,
+.leaflet-control-arrow-right:hover:before,
+.leaflet-control-arrow-up:hover:before,
+.leaflet-control-arrow-down:hover:before{
+  color: #777;
+}
+.leaflet-control-arrow-left:hover,
+.leaflet-control-arrow-right:hover,
+.leaflet-control-arrow-up:hover,
+.leaflet-control-arrow-down:hover,
+.leaflet-control-arrow-left:focus,
+.leaflet-control-arrow-right:focus,
+.leaflet-control-arrow-up:focus,
+.leaflet-control-arrow-down:focus{
+  background: #fff;
+  text-decoration: none;
+}
+.leaflet-control-arrow-left:before{
+  content: "\f060";
+}
+.leaflet-control-arrow-right:before{
+  content: "\f061";
+}
+.leaflet-control-arrow-up:before{
+  content: "\f062";
+}
+.leaflet-control-arrow-down:before{
+  content: "\f063";
+}