feat: push notifications

[sgammon]

Summary

Adds initial support wiring for Push Notifications (see: #11651).

This requires instrumentation down into tao, to call methods on the AppDelegate or NSApplication / UIApplication (for Apple platforms). Firebase Messaging (FCM) support is also under consideration.

• tauri: Handle new events
  • (that's this pr)
  • Forward/map PushRegistration event
  • Forward/map PushRegistrationFailed event
  • General cleanup (don't repeat typedefs, etc)
• tao: Hooks into UIApplication / NSApplication
  • feat(push): push notifications tao#1015
  • Support for macOS
  • Support for iOS
  • Any considerations for Android
  • Considerations for Windows
• tauri-plugin-push-notifications:
  • feat(push): push notifications plugin plugins-workspace#2066
  • Initially working plugin structure (here)
  • Facade for await pushToken(...)
  • Working local test to capture token
  • Add plugin sources to plugins-workspace
  • Interface for callback-based token access
• tauri-docs
  • docs: add push-notifications plugin documentation tauri-docs#2997
  • Add initial Push Notifications plugin page
  • Validate configuration with example app
• Platform support
  • macOS (APNS)
  • iOS (APNS)
  • Windows (WNS)
  • Android (FCM)

PR Tree

This PR is accompanied by a plugin, tauri-plugin-push-notifications, and a PR to tao:

• Plugin repo
• feat(push): push notifications tao#1015
• feat(push): push notifications plugin plugins-workspace#2066
• docs: add push-notifications plugin documentation tauri-docs#2997

Known Issues

• General
  • Token needs strong typing in guest code
• Docs
  • macOS and iOS devices need an entitlement, which should be mentioned in the docs.
• Tests
  • There are no tests yet.

Warning

This functionality is experimental and is gated behind the push-notifications feature for now.

How it works

(1) tao and tauri forward two new events: PushRegistration(PushToken) and PushRegistrationFailed(Error).
(2) a new plugin, tauri-plugin-push-notifications, listens for these events, holds the token or error, and exposes those values to guest code when requested.

sequenceDiagram
    tao->>+OS: Setup app delegate
    OS->>+tao: applicationDidFinishLaunching
    tao->>+OS: registerForRemoteNotifications()
    OS->>+tao: didFinishRegisteringWithToken()
    tao->>+tauri: PushRegistration(PushToken) Event
    tauri->>+Plugin: Forward event
    Plugin->>+Plugin: Retain token in-memory
    tauri->>+App: Launch app
    App<<->>+Plugin: await pushToken()

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[ChrisCates]

Any way I can help ship this?
That or, what's your ETA for completion brotha?

[sgammon]

@ChrisCates Very close to completion, i'm testing on macOS shortly. I haven't explored Android yet, so some research there might help (how best to integrate Firebase Cloud Messaging - FCM - into tao and tauri; ideally it could work within the plugin only).

Windows is looking solid but I'm not sure how to extract the token yet. That may remain experimental until later if only because I can't find any third party push services that support WNS at this time.

tl;dr I'd say we could get macOS and potentially iOS working within a few days. Android and WNS are probably easier/less complex, but may take a few days longer for research about how best to integrate. Regarding review and merge, I've no clue, this is my first PR to Tauri.