Update mimemailparser from May 2011 version to 8.0.4

Summary:
Bump to version 8.0.4 from 2024-09-11 per https://github.com/php-mime-mail-parser/php-mime-mail-parser/releases before this ancient code copy falls apart.
scripts/mail/mail_handler.php (used for incoming (!) mail) is the only consumer.

Closes T15940

Test Plan: Feed mail_handler.php with various test emails (formats: plain text, HTML, multipart; encodings: UTF-8, ASCII, ISO-8859-something) by manually replacing php://stdin with corresponding text files and adding some phlogs for output checking as I don't have mail server glue handy. Get only expected errors for broken emails.

Reviewers: O1 Blessed Committers, 20after4

Reviewed By: O1 Blessed Committers, 20after4

Subscribers: 20after4, tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Maniphest Tasks: T15940

Differential Revision: https://we.phorge.it/D25829