TF-3591 Implement CalendarEventCounter/accept method

lib/features/email/data/datasource/calendar_event_datasource.dart

@@ -23,4 +23,8 @@ abstract class CalendarEventDataSource {
     AccountId accountId,
     Set<Id> blobIds,
     String? language);
+
+  Future<CalendarEventAcceptResponse> acceptCounterEvent(
+    AccountId accountId,
+    Set<Id> blobIds);
 }

lib/features/email/data/datasource_impl/calendar_event_datasource_impl.dart

@@ -52,4 +52,14 @@ class CalendarEventDataSourceImpl extends CalendarEventDataSource {
       return await _calendarEventAPI.rejectEventInvitation(accountId, blobIds, language);
     }).catchError(_exceptionThrower.throwException);
   }
+  
+  @override
+  Future<CalendarEventAcceptResponse> acceptCounterEvent(
+    AccountId accountId,
+    Set<Id> blobIds,
+  ) {
+    return Future.sync(() async {
+      return await _calendarEventAPI.acceptCounterEvent(accountId, blobIds);
+    }).catchError(_exceptionThrower.throwException);
+  }
 }

lib/features/email/data/network/calendar_event_api.dart

@@ -13,6 +13,7 @@ import 'package:jmap_dart_client/jmap/mail/calendar/parse/calendar_event_parse_m
 import 'package:jmap_dart_client/jmap/mail/calendar/parse/calendar_event_parse_response.dart';
 import 'package:jmap_dart_client/jmap/mail/calendar/reply/calendar_event_accept_method.dart';
 import 'package:jmap_dart_client/jmap/mail/calendar/reply/calendar_event_accept_response.dart';
+import 'package:jmap_dart_client/jmap/mail/calendar/reply/calendar_event_counter_accept_method.dart';
 import 'package:jmap_dart_client/jmap/mail/calendar/reply/calendar_event_maybe_method.dart';
 import 'package:jmap_dart_client/jmap/mail/calendar/reply/calendar_event_maybe_response.dart';
 import 'package:jmap_dart_client/jmap/mail/calendar/reply/calendar_event_reject_method.dart';
@@ -192,4 +193,35 @@ class CalendarEventAPI {
       throw CannotReplyCalendarEventException(mapErrors: calendarEventRejectResponse.notRejected);
     }
   }
+
+  Future<CalendarEventAcceptResponse> acceptCounterEvent(
+    AccountId accountId,
+    Set<Id> blobIds,
+  ) async {
+    final requestBuilder = JmapRequestBuilder(_httpClient, ProcessingInvocation());
+    final calendarEventCounterAcceptMethod = CalendarEventCounterAcceptMethod(
+      accountId,
+      blobIds: blobIds.toList());
+    final calendarEventAcceptInvocation = requestBuilder.invocation(
+      calendarEventCounterAcceptMethod,
+    );
+    final response = await (requestBuilder
+        ..usings(calendarEventCounterAcceptMethod.requiredCapabilities))
+      .build()
+      .execute();
+
+    final calendarEventAcceptResponse = response.parse<CalendarEventAcceptResponse>(
+      calendarEventAcceptInvocation.methodCallId,
+      CalendarEventAcceptResponse.deserialize);
+
+    if (calendarEventAcceptResponse == null) {
+      throw NotAcceptableCalendarEventException();
+    }
+
+    if (calendarEventAcceptResponse.accepted?.isNotEmpty == true) {
+      return calendarEventAcceptResponse;
+    } else {
+      throw CannotReplyCalendarEventException(mapErrors: calendarEventAcceptResponse.notAccepted);
+    }
+  }
 }

lib/features/email/data/repository/calendar_event_repository_impl.dart

@@ -85,4 +85,13 @@ class CalendarEventRepositoryImpl extends CalendarEventRepository {
         : calendarEvent.description,
     );
   }
+  
+  @override
+  Future<CalendarEventAcceptResponse> acceptCounterEvent(
+    AccountId accountId,
+    Set<Id> blobIds,
+  ) {
+    return _calendarEventDataSource[DataSourceType.network]!
+      .acceptCounterEvent(accountId, blobIds);
+  }
 }