[TASK] Add MAIL/dsn setting to blinded configuration options

$GLOBALS['TYPO3_CONF_VARS']['MAIL']['dsn'] may contain credentials
and is therefore blinded in the configuration module.

Resolves: #96993
Releases: main, 11.5
Change-Id: I9a6ff7cc8f6c58fa3281125d5198bebb452a4ebc
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/74856


Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>