Should we allow non-ASCII letters in catalog/schema/table name ?

[evenyag]

In dbms like MySQL, user is allowed to use non-ASCII letters in table names, e.g.

`hühnervögel`
`你好`
`😊😊😊`

Now we use those names in our storage paths, keys in meta, thus limited the characters we could use. We might need to discuss whether those characters are allowed in table names.