TF-3515 Add save email as template feature

lib/features/composer/presentation/model/create_email_request.dart

@@ -31,7 +31,9 @@ class CreateEmailRequest with EquatableMixin {
   final MailboxId? outboxMailboxId;
   final MailboxId? sentMailboxId;
   final MailboxId? draftsMailboxId;
+  final MailboxId? templateMailboxId;
   final EmailId? draftsEmailId;
+  final EmailId? templateEmailId;
   final EmailId? answerForwardEmailId;
   final EmailId? unsubscribeEmailId;
   final MessageIdsHeaderValue? messageId;
@@ -64,7 +66,9 @@ class CreateEmailRequest with EquatableMixin {
     this.outboxMailboxId,
     this.sentMailboxId,
     this.draftsMailboxId,
+    this.templateMailboxId,
     this.draftsEmailId,
+    this.templateEmailId,
     this.answerForwardEmailId,
     this.unsubscribeEmailId,
     this.messageId,
@@ -99,7 +103,9 @@ class CreateEmailRequest with EquatableMixin {
     outboxMailboxId,
     sentMailboxId,
     draftsMailboxId,
+    templateMailboxId,
     draftsEmailId,
+    templateEmailId,
     answerForwardEmailId,
     unsubscribeEmailId,
     references,

lib/features/composer/presentation/model/saved_composing_email.dart

@@ -6,10 +6,10 @@ import 'package:jmap_dart_client/jmap/mail/email/email_address.dart';
 import 'package:json_annotation/json_annotation.dart';
 import 'package:model/email/attachment.dart';
 
-part 'saved_email_draft.g.dart';
+part 'saved_composing_email.g.dart';
 
 @JsonSerializable(includeIfNull: false, explicitToJson: true)
-class SavedEmailDraft with EquatableMixin {
+class SavedComposingEmail with EquatableMixin {
   final String content;
   final String subject;
   final Set<EmailAddress> toRecipients;
@@ -21,7 +21,7 @@ class SavedEmailDraft with EquatableMixin {
   final bool hasReadReceipt;
   final bool isMarkAsImportant;
 
-  SavedEmailDraft({
+  SavedComposingEmail({
     required this.content,
     required this.subject,
     required this.toRecipients,
@@ -34,12 +34,26 @@ class SavedEmailDraft with EquatableMixin {
     this.isMarkAsImportant = false,
   });
 
-  factory SavedEmailDraft.fromJson(Map<String, dynamic> json) => _$SavedEmailDraftFromJson(json);
+  factory SavedComposingEmail.fromJson(Map<String, dynamic> json) => _$SavedComposingEmailFromJson(json);
 
-  Map<String, dynamic> toJson() => _$SavedEmailDraftToJson(this);
+  Map<String, dynamic> toJson() => _$SavedComposingEmailToJson(this);
 
   String asString() => jsonEncode(toJson());
 
+  factory SavedComposingEmail.empty() {
+    return SavedComposingEmail(
+      subject: '',
+      content: '',
+      toRecipients: {},
+      ccRecipients: {},
+      bccRecipients: {},
+      replyToRecipients: {},
+      attachments: [],
+      identity: null,
+      hasReadReceipt: false,
+    );
+  }
+
   @override
   List<Object?> get props => [
     content,