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.

api_docs/changelog.md

@@ -20,6 +20,16 @@ format used by the Zulip server that they are interacting with.
 
 ## Changes in Zulip 11.0
 
+**Feature level 406**
+
+* [`POST /register`](/api/register-queue): Added `push_devices`
+  field to response.
+* [`GET /events`](/api/get-events): A `push_device` event is sent
+  to clients when registration to bouncer either succeeds or fails.
+* [`POST /mobile_push/register`](/api/register-push-device): Added
+  an endpoint to register a device to receive end-to-end encrypted
+  mobile push notifications.
+
 **Feature level 405**
 
 * [Message formatting](/api/message-formatting): Added new HTML

api_docs/include/rest-endpoints.md

@@ -155,6 +155,7 @@
 * [Fetch an API key (production)](/api/fetch-api-key)
 * [Fetch an API key (development only)](/api/dev-fetch-api-key)
 * [Send a test notification to mobile device(s)](/api/test-notify)
+* [Register E2EE push device](/api/register-push-device)
 * [Add an APNs device token](/api/add-apns-token)
 * [Remove an APNs device token](/api/remove-apns-token)
 * [Add an FCM registration token](/api/add-fcm-token)

api_docs/unmerged.d/ZF-1653f2.md

@@ -1,2 +0,0 @@
-* [`POST /register`](/api/register-queue): Added `push_devices`
-  field to response.