Update the caching framework to FLOW3 version 868e073b98

Main changes:

[!!!][FEATURE] Make cache backends more flexible
This change makes cache backends more flexible. It adds a new
interface "TaggableBackendInterface" and a new "SimpleFileBackend".
The latter does not support tagging but is faster in certain cases
(where with a lot of tags/entries flushing everything is faster than
flushing by tag).
If you have implemented a cache backend and support tagging, you must
add the "TaggableBackendInterface" to the list of interfaces implemented
by your backend.

[BUGFIX] Fix default lifetime use in cache backend

[FEATURE] Freezable Cache Backend
Introduce a new type of cache backends which supports freezing.
In a frozen state no modifications are allowed and thus enables the
cache implementation to optimize its tasks for speed.
The FileBackend was extended to support freezing.

Change-Id: Id4c609ecfcbb223cf6bc99202ef41b436e21ef78
Resolves: #39430
Related: #36563
Related: #33562
Related: #32398
Related: #36564
Releases: 6.0
Reviewed-on: http://review.typo3.org/13390
Reviewed-by: Helmut Hummel
Tested-by: Helmut Hummel
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn