[BUGFIX] Fix Misleading CommandController naming for Language update

Due to CommandControllers' nature, an UpdateCommandController leads to the
execution of `cli_dispatch.phpsh extbase update:update`.

This patch fixes it to `cli_dispatch.phpsh extbase language:update`.

Also contains a minor change and adds a type-hint for IDE's.

Resolves: #54128
Releases: 6.2
Change-Id: I1b21b8f715bfd1928f1e857846c0542d90705b6f
Reviewed-on: https://review.typo3.org/24511
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Wouter Wolters
Tested-by: Wouter Wolters