MM-27312 Allow uploading 10 files per post (#16235)

* Allow uploading 10 files per post

* Increase Post.Fileids column size to fit 10 files

* Add Post.Fileids column changes to DB v531

* Fix current_schema_version

Co-authored-by: Claudio Costa <cstcld91@gmail.com>

* Update store/sqlstore/upgrade.go

Co-authored-by: Claudio Costa <cstcld91@gmail.com>

* Fix schema version

Co-authored-by: Diogo Lima Nicolau <diogo.lima.nicolau@cern.ch>
Co-authored-by: Harrison Healey <harrisonmhealey@gmail.com>
Co-authored-by: Claudio Costa <cstcld91@gmail.com>
Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

scripts/mattermost-mysql-5.0.sql

@@ -626,7 +626,7 @@ CREATE TABLE `Posts` (
   `Props` text,
   `Hashtags` text,
   `Filenames` text,
-  `FileIds` varchar(150) DEFAULT NULL,
+  `FileIds` varchar(300) DEFAULT NULL,
   `HasReactions` tinyint(1) DEFAULT NULL,
   PRIMARY KEY (`Id`),
   KEY `idx_posts_update_at` (`UpdateAt`),