Support charset + collation combination in connection options

When using MariaDB 11+ UCA1400 collations (e.g. uca1400_ai_ci), there was no way to specify both a charset and a collation together. The collation name UCA1400_AI_CI exists for multiple charsets (utf8mb3, utf8mb4, ucs2, utf16, utf32), so specifying only the collation name was ambiguous.
before that, collation where prefix with charset so that wasn't a problem, now it is.

goal is to permit charset + collation option at the same time, like :

const conn = await mariadb.createConnection({

  charset: 'utf8mb4',

  collation: 'uca1400_ai_ci'

});

at the same time, when setting only collation name, and multiple results corresponds, like 'uca1400_ai_ci', utf8mb4 will have to be prefered by default.