Made google-play login working again, and fixed numerous bugs

lib/model/endpointData.dart

@@ -0,0 +1,70 @@
+
+import 'accountData.dart';
+
+enum EndpointMode {
+  live,
+  stage,
+}
+
+class EndpointOptions {
+  Endpoint live;
+  Endpoint? staged;
+  EndpointOptions({required this.live, required this.staged});
+
+  Endpoint get(EndpointMode mode) {
+    if(staged == null || mode == EndpointMode.live) return live;
+    return staged!;
+  }
+}
+
+class Endpoint {
+  String domain;
+  String path;
+
+  Endpoint({required this.domain, this.path = ""});
+
+  String full() {
+    return domain + path;
+  }
+}
+
+class EndpointData {
+  static final EndpointData _instance = EndpointData._construct();
+
+  factory EndpointData() {
+    return _instance;
+  }
+
+  EndpointData._construct();
+
+  EndpointMode getEndpointMode() {
+    late String existingName;
+    existingName = AccountData().getUsername();
+    return existingName.startsWith("google") ? EndpointMode.stage : EndpointMode.live;
+  }
+
+  Endpoint webuntis() {
+    return EndpointOptions(
+      live: Endpoint(
+        domain: "peleus.webuntis.com",
+      ),
+      staged: Endpoint(
+        domain: "mhsl.eu",
+        path: "/marianum/marianummobile/webuntis/public/index.php/api"
+      ),
+    ).get(getEndpointMode());
+  }
+
+  Endpoint nextcloud() {
+    return EndpointOptions(
+      live: Endpoint(
+        domain: "cloud.marianum-fulda.de",
+      ),
+      staged: Endpoint(
+        domain: "mhsl.eu",
+        path: "/marianum/marianummobile/cloud",
+      )
+    ).get(getEndpointMode());
+  }
+
+}