[MM-61691] Deleting drafts when permanently deleting a user (#30233)

* deleting drafts on permanently deleting user

* verified count of drafts before deleting

* i18n fix

* use ExecBuilder

* changed error message to specify user

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Co-authored-by: Mattermost Build <build@mattermost.com>
Co-authored-by: Harshil Sharma <harshilsharma63@gmail.com>

server/channels/store/store.go

@@ -1039,6 +1039,7 @@ type DraftStore interface {
 	GetLastCreateAtAndUserIdValuesForEmptyDraftsMigration(createAt int64, userID string) (int64, string, error)
 	DeleteEmptyDraftsByCreateAtAndUserId(createAt int64, userID string) error
 	DeleteOrphanDraftsByCreateAtAndUserId(createAt int64, userID string) error
+	PermanentDeleteByUser(userId string) error
 }
 
 type PostAcknowledgementStore interface {