[TASK] Move CF last_synched_revision file to ext:core/Classes/Cache

Change-Id: I32887386c6a5b4162a12b419c5f34e1ddc061a35
Resolves: #46262
Releases: 6.1
Reviewed-on: https://review.typo3.org/18894
Reviewed-by: Georg Ringer
Tested-by: Georg Ringer
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn