Push Notifications (#66)

Fixes #35.

Things to do:
- [x] Register with local distributor
- [x] Register with homeserver
- [x] Recieve messages
- [x] Show notifications
- [ ] Notifications page (could come later)

Reviewed-on: #66

pubspec.lock

@@ -495,6 +495,46 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_local_notifications:
+    dependency: "direct main"
+    description:
+      name: flutter_local_notifications
+      sha256: "1447ba911c60f2ba3f25dae1af151ec187162566b0f57e37771bf0b400f013ad"
+      url: "https://pub.dev"
+    source: hosted
+    version: "22.3.0"
+  flutter_local_notifications_linux:
+    dependency: "direct main"
+    description:
+      name: flutter_local_notifications_linux
+      sha256: "9ca97e63776f29ab1b955725c09999fc2c150523269db150c39274f2a43c5a8b"
+      url: "https://pub.dev"
+    source: hosted
+    version: "8.0.1"
+  flutter_local_notifications_platform_interface:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_platform_interface
+      sha256: "43c3761d916c9bd3d5c7ebbc44d82f4990329840c0c5d62ad5260cc1b5d399bd"
+      url: "https://pub.dev"
+    source: hosted
+    version: "12.2.0"
+  flutter_local_notifications_web:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_web
+      sha256: "516afaf97a2d1e67a036c6617321b00d205d72f7a67b6eccf936cd565f985878"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
+  flutter_local_notifications_windows:
+    dependency: transitive
+    description:
+      name: flutter_local_notifications_windows
+      sha256: "6f43bdd03b171b7a90f22647506fea33e2bb12294b7c7c7a3d690e960a382945"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.1"
   flutter_localizations:
     dependency: "direct main"
     description: flutter
@@ -1429,6 +1469,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.7.1"
+  timezone:
+    dependency: transitive
+    description:
+      name: timezone
+      sha256: "981d1020d6ef8fe1e7b3de5054e5b25579ae7c403d7734adc508ffc47668e9cb"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.11.1"
   typed_data:
     dependency: transitive
     description:
@@ -1437,6 +1485,54 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.0"
+  unifiedpush:
+    dependency: "direct main"
+    description:
+      name: unifiedpush
+      sha256: "8ed9767f750a1dc6159a77e2171641d0cb825dc87682d1ce1b8618689b79f58e"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.2.0"
+  unifiedpush_android:
+    dependency: transitive
+    description:
+      name: unifiedpush_android
+      sha256: a902e505e91c8e28b54b379bb27f255f66df409274a97af24d6719f12f0d13dc
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.5.0"
+  unifiedpush_linux:
+    dependency: transitive
+    description:
+      name: unifiedpush_linux
+      sha256: c062d5eedd1cec70bcd33270cc4e01ae0ff6501f33d471167c06b34a968adfeb
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
+  unifiedpush_platform_interface:
+    dependency: transitive
+    description:
+      name: unifiedpush_platform_interface
+      sha256: "83372bc8d794b8b12ef6993b518d7be907dcfc2191bdf6de0ece5c4445d89880"
+      url: "https://pub.dev"
+    source: hosted
+    version: "4.0.0"
+  unifiedpush_storage_interface:
+    dependency: transitive
+    description:
+      name: unifiedpush_storage_interface
+      sha256: b8d423a4695efc616aa21d8ab48fb5ef99d6288c68b56282b8faac1579ceabd9
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
+  unifiedpush_storage_shared_preferences:
+    dependency: "direct main"
+    description:
+      name: unifiedpush_storage_shared_preferences
+      sha256: eda9c52bac0058f81e0d9c65e33eedc12c5901d2e68ad47fdf68175ddf00a3b4
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
   universal_platform:
     dependency: transitive
     description:
@@ -1613,6 +1709,22 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.0.3"
+  webcrypto:
+    dependency: "direct dev"
+    description:
+      name: webcrypto
+      sha256: "6b43001c4110856ff7fa5e5e65e7b2d44bec1d8b54a4d84d5fa2c7622267c5c1"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.0"
+  webpush_encryption:
+    dependency: transitive
+    description:
+      name: webpush_encryption
+      sha256: "5b83272b91acda6ae515fcd980c94f06bf413702282497c5a68f5dfc64fed27f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.1"
   win32:
     dependency: transitive
     description: