Provide tools to encode/decode mysql-encoded file system names

As non-ASCII letters are encoded in database directory names and table file nasenames there should be tools that can be used to perform conversion to human-readable unicode output (and back from unicode to encoded form?), either as SQL function, command line tool, or both.

e.g. @6e2c@8a66@8cc7@6599@5eab' <-> 測試資料

See also:

• https://mariadb.com/kb/en/library/identifier-to-file-name-mapping/
• https://mariadb.com/resources/blog/demystifying-identifier-mapping/

and especially the comment from HeidiSQL on the later one.