TF-320 Add capability validator for Jmap request

lib/main/error/capability_validator.dart

@@ -0,0 +1,20 @@
+import 'package:jmap_dart_client/jmap/core/capability/capability_identifier.dart';
+import 'package:jmap_dart_client/jmap/core/session/session.dart';
+import 'package:tmail_ui_user/main/error/request_error.dart';
+
+void requireCapability(Session session, List<CapabilityIdentifier> requiredCapabilities) {
+  final matchedCapabilities = session.capabilities.keys
+      .fold<Set<CapabilityIdentifier>>(
+        Set<CapabilityIdentifier>(),
+        (previousValue, element) {
+          if (requiredCapabilities.contains(element)) {
+            previousValue.add(element);
+          }
+          return previousValue;
+        }
+      );
+  final missingCapabilities = requiredCapabilities.toSet().difference(matchedCapabilities);
+  if (missingCapabilities.length > 0) {
+    throw SessionMissingCapability(missingCapabilities);
+  }
+}

lib/main/error/request_error.dart

@@ -0,0 +1,11 @@
+import 'package:equatable/equatable.dart';
+import 'package:jmap_dart_client/jmap/core/capability/capability_identifier.dart';
+
+class SessionMissingCapability extends Equatable implements Exception {
+  final Set<CapabilityIdentifier> capabilityIdentifiers;
+
+  SessionMissingCapability(this.capabilityIdentifiers);
+
+  @override
+  List<Object?> get props => [capabilityIdentifiers];
+}