Web Push Notifications (#3243)

* feat: Register push subscription

* feat: Notify when mentioned

* feat: Boost, favourite, reply, follow, follow request

* feat: Notification interaction

* feat: Handle change of public key

* feat: Unsubscribe if things go wrong

* feat: Do not send normal notifications if push is enabled

* feat: Focus client if open

* refactor: Move push logic to WebPushSubscription

* feat: Better title and body

* feat: Localize messages

* chore: Fix lint errors

* feat: Settings

* refactor: Lazy load

* fix: Check if push settings exist

* feat: Device-based preferences

* refactor: Simplify logic

* refactor: Pull request feedback

* refactor: Pull request feedback

* refactor: Create /api/web/push_subscriptions endpoint

* feat: Spec PushSubscriptionController

* refactor: WebPushSubscription => Web::PushSubscription

* feat: Spec Web::PushSubscription

* feat: Display first media attachment

* feat: Support direction

* fix: Stuff broken while rebasing

* refactor: Integration with session activations

* refactor: Cleanup

* refactor: Simplify implementation

* feat: Set VAPID keys via environment

* chore: Comments

* fix: Crash when no alerts

* fix: Set VAPID keys in testing environment

* fix: Follow link

* feat: Notification actions

* fix: Delete previous subscription

* chore: Temporary logs

* refactor: Move migration to a later date

* fix: Fetch the correct session activation and misc bugs

* refactor: Move migration to a later date

* fix: Remove follow request (no notifications)

* feat: Send administrator contact to push service

* feat: Set time-to-live

* fix: Do not show sensitive images

* fix: Reducer crash in error handling

* feat: Add badge

* chore: Fix lint error

* fix: Checkbox label overlap

* fix: Check for payload support

* fix: Rename action "type" (crash in latest Chrome)

* feat: Action to expand notification

* fix: Lint errors

* fix: Unescape notification body

* fix: Do not allow boosting if the status is hidden

* feat: Add VAPID keys to the production sample environment

* fix: Strip HTML tags from status

* refactor: Better error messages

* refactor: Handle browser not implementing the VAPID protocol (Samsung Internet)

* fix: Error when target_status is nil

* fix: Handle lack of image

* fix: Delete reference to invalid subscriptions

* feat: Better error handling

* fix: Unescape HTML characters after tags are striped

* refactor: Simpify code

* fix: Modify to work with #4091

* Sort strings alphabetically

* i18n: Updated Polish translation

it annoys me that it's not fully localized :P

* refactor: Use current_session in PushSubscriptionController

* fix: Rebase mistake

* fix: Set cacheName to mastodon

* refactor: Pull request feedback

* refactor: Remove logging statements

* chore(yarn): Fix conflicts with master

* chore(yarn): Copy latest from master

* chore(yarn): Readd offline-plugin

* refactor: Use save! and update!

* refactor: Send notifications async

* fix: Allow retry when push fails

* fix: Save track for failed pushes

* fix: Minify sw.js

* fix: Remove account_id from fabricator

Gemfile.lock

@@ -181,6 +181,7 @@ GEM
     hashdiff (0.3.4)
     highline (1.7.8)
     hiredis (0.6.1)
+    hkdf (0.3.0)
     htmlentities (4.3.4)
     http (2.2.2)
       addressable (~> 2.3)
@@ -209,6 +210,7 @@ GEM
     jmespath (1.3.1)
     json (2.1.0)
     jsonapi-renderer (0.1.2)
+    jwt (1.5.6)
     kaminari (1.0.1)
       activesupport (>= 4.1.0)
       kaminari-actionview (= 1.0.1)
@@ -475,6 +477,9 @@ GEM
       activesupport (>= 4.2)
       multi_json (~> 1.2)
       railties (>= 4.2)
+    webpush (0.3.2)
+      hkdf (~> 0.2)
+      jwt
     websocket-driver (0.6.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.2)
@@ -573,6 +578,7 @@ DEPENDENCIES
   uglifier (~> 3.2)
   webmock (~> 3.0)
   webpacker (~> 2.0)
+  webpush
 
 RUBY VERSION
    ruby 2.4.1p111