Add dropdown template

brian_dashboard_manager/templating/templates/shared/dropdown.json.j2

+{
+    "aliasColors": {},
+    "collapsed": false,
+    "datasource": null,
+    "fill": null,
+    "fillGradient": null,
+    "gridPos": {
+        "h": 1,
+        "w": 24,
+        "x": 0,
+        "y": {{ y }}
+    },
+    "id": {{ id }},
+    "legend": null,
+    "lines": null,
+    "linewidth": null,
+    "search": null,
+    "stack": null,
+    "tags": null,
+    "targets": null,
+    "title": "{{ title }}",
+    "type": "row",
+    "xaxis": null,
+    "yaxes": null,
+    "yaxis": null
+}
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