Add branch_filter to hooks API endpoints (#26599)

We now include the branch filler in the response.

- Closes #26591 

# Before

![image](https://github.com/go-gitea/gitea/assets/20454870/73933940-c1a7-4573-abae-f340b63028b2)

# After

![image](https://github.com/go-gitea/gitea/assets/20454870/3b3c4a85-0f7c-48c7-8617-def7a66c671d)

---------

Signed-off-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: Giteabot <teabot@gitea.io>

templates/swagger/v1_json.tmpl

@@ -19137,6 +19137,10 @@
           "type": "string",
           "x-go-name": "AuthorizationHeader"
         },
+        "branch_filter": {
+          "type": "string",
+          "x-go-name": "BranchFilter"
+        },
         "config": {
           "type": "object",
           "additionalProperties": {