[manual] Extend /api/v1/streams API endpoint.

Previously it only provided the list of all public streams; now it
allows one to specify any union of some of the following:
* all public streams
* all streams the user subscribed to

(the most relevant being the union of those two, which is what we want
for the "streams" page).

Or:
* all streams in realm (superuser only)

The manual task required is that when this is pushed to prod, we need
to also deploy the new sync-public-streams version to zmirror.

(imported from commit 27848b8bd136e2777f399b7d05b2fdcec35e4e21)

bots/sync-public-streams

@@ -16,7 +16,7 @@ def fetch_public_streams():
     public_streams = set()
 
     try:
-        res = zulip_client.get_public_streams()
+        res = zulip_client.get_streams(include_all_active=True)
         if res.get("result") == "success":
             streams = res["streams"]
         else: