Add user agent field to RTMP, RTSP, WebRTC, and HLS (#5753)

Surface user agent in the auth HTTP webhook payload as "userAgent"
and in the API structs for RTMP, RTSP, WebRTC and HLS connections.

---------

Co-authored-by: aler9 <46489434+aler9@users.noreply.github.com>

api/openapi.yaml

@@ -1213,6 +1213,8 @@ components:
           type: string
         user:
           type: string
+        userAgent:
+          type: string
         isCDN:
           type: boolean
         outboundBytes:
@@ -1281,6 +1283,8 @@ components:
           type: string
         user:
           type: string
+        userAgent:
+          type: string
         inboundBytes:
           type: integer
           format: uint64
@@ -1376,6 +1380,8 @@ components:
           type: string
         user:
           type: string
+        userAgent:
+          type: string
         transport:
           type: string
           nullable: true
@@ -1774,6 +1780,8 @@ components:
           type: string
         user:
           type: string
+        userAgent:
+          type: string
         inboundBytes:
           type: integer
           format: uint64