TF-3181 Display contact support button on web app

(cherry picked from commit cfc027522962fbf7092c8a15876d6c61f0aca6fc)

model/lib/model.dart

@@ -79,4 +79,6 @@ export 'oidc/token_id.dart';
 export 'oidc/token_oidc.dart';
 // Upload
 export 'upload/file_info.dart';
-export 'upload/upload_response.dart';
+export 'upload/upload_response.dart';
+// Support
+export 'support/contact_support_capability.dart';

model/lib/support/contact_support_capability.dart

@@ -0,0 +1,24 @@
+
+import 'package:jmap_dart_client/jmap/core/capability/capability_properties.dart';
+import 'package:json_annotation/json_annotation.dart';
+
+part 'contact_support_capability.g.dart';
+
+@JsonSerializable(explicitToJson: true, includeIfNull: false)
+class ContactSupportCapability extends CapabilityProperties {
+  final String? httpLink;
+  final String? supportMailAddress;
+
+  ContactSupportCapability({this.httpLink, this.supportMailAddress});
+
+  factory ContactSupportCapability.fromJson(Map<String, dynamic> json) => _$ContactSupportCapabilityFromJson(json);
+
+  Map<String, dynamic> toJson() => _$ContactSupportCapabilityToJson(this);
+
+  static ContactSupportCapability deserialize(Map<String, dynamic> json) {
+    return ContactSupportCapability.fromJson(json);
+  }
+
+  @override
+  List<Object?> get props => [httpLink, supportMailAddress];
+}