mail/phpmailer7: add new Port

This is exactly the same as version 6.11.1 but bumps the major version
number to indicate the presence of a BC break in child classes. The
changes in 6.11.0 and 6.11.1 have been reverted in 6.12.0. If you have
code that depends on those changes, please upgrade to 7.0.0 instead.
Apologies for the mix up.

Specifically, lang(), setLanguage(), and $language are now static, and
should be called statically.

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