[API] Only Return Json (#13511)

* Let Branch and Raw Endpoint return json error if not found

* Revert "RM RepoRefByTypeForAPI and move needed parts into GetRawFile directly"

This reverts commit d826d08577b23765cb3c257e7a861191d1aa9a04.

* more similar to RepoRefByType

* dedub-code

* API should just speak JSON

* nice name

Co-authored-by: zeripath <art27@cantab.net>

templates/swagger/v1_json.tmpl

@@ -2541,6 +2541,9 @@
         "responses": {
           "200": {
             "$ref": "#/responses/Branch"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
           }
         }
       },
@@ -2582,6 +2585,9 @@
           },
           "403": {
             "$ref": "#/responses/error"
+          },
+          "404": {
+            "$ref": "#/responses/notFound"
           }
         }
       }