OAuth Support (#53)

Rips out the old auth method, adds OAuth support. Fixes #51.

Tested Platforms:
- [x] Linux
    - [x] Flatpak
    - [x] Native (Nix)
- [x] Android
- [ ] Windows
- [ ] MacOS

Reviewed-on: Nexus/nexus#53

android/app/build.gradle

@@ -30,7 +30,7 @@ if (keystorePropertiesFile.exists()) {
 }
 
 android {
-    namespace = "nexus.federated.Nexus"
+    namespace = "nexus.federated.nexus"
     ndkVersion = flutter.ndkVersion
     compileSdk = 34
 
@@ -45,7 +45,7 @@ android {
     }
 
     defaultConfig {
-        applicationId = "nexus.federated.Nexus"
+        applicationId = "nexus.federated.nexus"
         minSdk = 29
         targetSdkVersion flutter.targetSdkVersion
         versionCode = flutterVersionCode.toInteger()

android/app/src/main/AndroidManifest.xml

@@ -22,6 +22,14 @@
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
             android:hardwareAccelerated="true"
             android:windowSoftInputMode="adjustResize">
+			<meta-data android:name="flutter_deeplinking_enabled" android:value="false" />
+			<intent-filter>
+				<action android:name="android.intent.action.VIEW" />
+				<category android:name="android.intent.category.DEFAULT" />
+				<category android:name="android.intent.category.BROWSABLE" />
+
+				<data android:scheme="nexus.federated.nexus" />
+			</intent-filter>
             <meta-data
               android:name="io.flutter.embedding.android.NormalTheme"
               android:resource="@style/NormalTheme"

android/app/src/main/kotlin/com/example/mobile_requester_app/MainActivity.kt

@@ -1,4 +1,4 @@
-package nexus.federated.Nexus
+package nexus.federated.nexus
 
 import io.flutter.embedding.android.FlutterActivity