Feature: #99436 - List commands in scheduler module

See forge#99436

Description

Commands based on Symfony commands are the successor of regular tasks since TYPO3 v8.

The scheduler submodule Available scheduler commands & tasks has been extended to list not only available scheduler tasks, but CLI commands that can be added as scheduler tasks.

Impact

The submodule Available scheduler commands & tasks has been improved to list schedulable commands as well. This improves the overview and makes it easier to set up commands.