Allow special characters in folder name when using e-mail filter

Summary

When trying to create a e-mail filter to move e-mails to a folder with a special character like a apostrophe ('), a error is shown that the regex doesn't allow this.

Steps to reproduce

Create a e-mail folder with a apostrophe in the name, e.g. I'm a folder
Try to create a e-mail filter to move e-mail to this folder when a certain condition is met.

Correct behaviour

Special characters that are allowed in mailfolder names should be allowed in the regex.

Environment

Server OS + version: Debian 10
ISPConfig version: 3.2.7p1

Proposed fix

Change the regex in https://git.ispconfig.org/ispconfig/ispconfig3/-/blob/develop/interface/web/mail/form/mail_user_filter.tform.php#L124 and https://git.ispconfig.org/ispconfig/ispconfig3/-/blob/develop/interface/web/mailuser/form/mail_user_filter.tform.php#L125
(while we're at it, check why it's on different lines when the file should be identical)