[TASK] Migrate get.typo3.org cache file fetching into separate CLI command

The downloading of the current corejson file is happening in an
outdated scheduler task, which is now needed anymore,
as all jobs within the task are now handled through a CLI command, the
latest being added is "ter:fetchCoreVersion".

This way, the original "UpdateCurrentVersionListTask" can be removed,
and in addition, the actual path of the cache file is now located in
one single PHP class and encapsulated there.
7 jobs for feature/encapsulate-core-versions-fetching in 9 minutes and 26 seconds (queued for 2 seconds)
Status Name Job ID Coverage
  Maintenance
manual Get dump for local environment #22070
allowed to fail manual
 
  Test
passed test:composer #22073

00:02:13

passed test:php #22072

00:01:47

passed test:typoscript #22071

00:02:02

passed test:unit #22074

00:03:28

 
  Build
passed build #22075

00:02:55

 
  Layout
passed layout #22076

00:03:01