[FEATURE] Show application context in the Environment module

The "Environment Overview" card in the admin tool will now show the
application context the TYPO3 instance is running with.

Resolves: #90136
Releases: master
Change-Id: Ia9583ac093cdeba341e8cd079bbac341098a3b76
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/63259


Tested-by: TYPO3com <noreply@typo3.com>
Tested-by: Nikita Hovratov <nikita.h@live.de>
Tested-by: Georg Ringer <georg.ringer@gmail.com>
Tested-by: Daniel Goerz <daniel.goerz@posteo.de>
Reviewed-by: Nikita Hovratov <nikita.h@live.de>
Reviewed-by: Georg Ringer <georg.ringer@gmail.com>
Reviewed-by: Daniel Goerz <daniel.goerz@posteo.de>