ENH: Map is disabled by default, example json file exists now.

conf/core/json/ext_map.json

+{
+    "disabled": true
+}

src/core/js/ext_map.js

@@ -742,6 +742,9 @@ var caosdb_map = new function () {
             var toggle_button = undefined;
             try {
                 const config = await this.load_config();
+                if (config.disabled) {
+                    return;
+                }
                 if (!config.views || config.views.length === 0) {
                     logger.warn("no views in config");
                     return;