feat(integrations): ability to add stringified event (#6642)

You might want to include entire event, but as a different field.

src/lib/addons/webhook-definition.ts

@@ -86,10 +86,11 @@ const webhookDefinition: IAddonDefinition = {
   "event": "{{event.type}}",
   "createdBy": "{{event.createdBy}}",
   "featureToggle": "{{event.data.name}}",
-  "timestamp": "{{event.data.createdAt}}"
+  "timestamp": "{{event.data.createdAt}}",
+  "json": {{{eventJson}}}
 }`,
             description:
-                "(Optional) You may format the body using a mustache template. If you don't specify anything, the format will similar to the events format (https://docs.getunleash.io/reference/api/legacy/unleash/admin/events)",
+                "(Optional) You may format the body using a mustache template. If you don't specify anything, the format will similar to the events format (https://docs.getunleash.io/reference/api/legacy/unleash/admin/events). You can use {{{eventJson}}} to include entire serialized event.",
             type: 'textfield',
             required: false,
             sensitive: false,

src/lib/addons/webhook.ts

@@ -22,6 +22,8 @@ export default class Webhook extends Addon {
             parameters;
         const context = {
             event,
+            // Stringify twice to avoid escaping in Mustache
+            eventJson: JSON.stringify(JSON.stringify(event)),
         };
 
         let body: string | undefined;