Prefer frontend_title for mailing groups in {mailing.group}

The {mailing.group} token in CiviMail currently displays the title field from groups. Now we can set a different frontend_title it would be good to use this if set.

Currently there is a hard-coded SQL query - https://lab.civicrm.org/dev/core/-/blob/master/CRM/Mailing/BAO/Mailing.php#L1418 - I wonder if API4 could be used instead?

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