cross upgrade from MySQL - have precheck tool

MySQL has a check if its able to be upgrade before it does it. This is largely internal in the checks of the document/code:
https://dev.mysql.com/doc/refman/8.0/en/mysqlcheck.html#option_mysqlcheck_check-upgrade
https://dev.mysql.com/doc/refman/8.0/en/check-table.html#check-table-version-compatibility

A similar test for example was suggested that we need to do in MariaDB. Given the large kb pages on incompatibilities I think this is something that can at least be partially automated in a check program.

The goal is to advice users if an existing MySQL instance has any incompatibilities to note before a user tries to cross-upgrade to MariaDB.

So the goal would be to check on a database/global scale looking at tables, at features used, at settings, at character sets in table and determine the migratablilty