zerver: Add endpoint to register a push device to server.

This commit adds an endpoint to register a push device
to receive E2EE push notifications.

zerver/lib/remote_server.py

@@ -21,9 +21,11 @@ from zerver.actions.realm_settings import (
 )
 from zerver.lib import redis_utils
 from zerver.lib.exceptions import (
+    InvalidBouncerPublicKeyError,
     JsonableError,
     MissingRemoteRealmError,
     RemoteRealmServerMismatchError,
+    RequestExpiredError,
 )
 from zerver.lib.outgoing_http import OutgoingSession
 from zerver.lib.queue import queue_event_on_commit
@@ -217,6 +219,12 @@ def send_to_push_bouncer(
             # The callers requesting this endpoint want the exception to propagate
             # so they can catch it.
             raise RemoteRealmServerMismatchError
+        elif endpoint == "push/e2ee/register" and code == "INVALID_BOUNCER_PUBLIC_KEY":
+            raise InvalidBouncerPublicKeyError
+        elif endpoint == "push/e2ee/register" and code == "REQUEST_EXPIRED":
+            raise RequestExpiredError
+        elif endpoint == "push/e2ee/register" and code == "MISSING_REMOTE_REALM":
+            raise MissingRemoteRealmError
         else:
             # But most other errors coming from the push bouncer
             # server are client errors (e.g. never-registered token)