Update multipart form data logic

All form values are simply added to the payload map without processing.
JSON parsing of values happens later.

test/hooks.json.tmpl

@@ -167,6 +167,30 @@
       ],
     }
   },
+  {
+    "id": "plex",
+    "execute-command": "{{ .Hookecho }}",
+    "command-working-directory": "/",
+    "response-message": "success",
+    "parse-parameters-as-json": [
+      {
+        "source": "payload",
+        "name": "payload"
+      }
+    ],
+    "trigger-rule":
+    {
+      "match":
+      {
+        "type": "value",
+        "parameter": {
+          "source": "payload",
+          "name": "payload.event"
+        },
+        "value": "media.play"
+      }
+    }
+  },
   {
     "id": "capture-command-output-on-success-not-by-default",
     "pass-arguments-to-command": [