[BUGFIX] Add missing language option to EmailToSender

The EmailFinisher class evaluates the defined "translation language"
which can be used to define the language of the mail content
independent of the current frontend language. The corresponding
option is however missing in the EmailToSender configuration.

This leads to side effects if e.g. EmailToReceiver is configured with
this option before EmailToSender. The EmailToSender finisher then
automatically also uses this language without any possibility to
prevent this behaviour.

Therefore the missing configuration option for defining a
translation language is now also available in the EmailToSender
finisher configuration like already claimed in the documentation.

Resolves: #92304
Releases: master, 10.4
Change-Id: Id81a5f616d439b4e4e844e270cadde3888ace46d
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/65733


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Benni Mack <benni@typo3.org>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Benni Mack <benni@typo3.org>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>