Instead of calling the cache backend for each tag to flush
individually, the list of tags is passed to the backend with
the newly introduced `flushByTags` method in
neos/flow-development-collection#2718.

This allows each type of backend to optimise the flushing
of all tags, which can lead to huge performance improvements.
Especially when content is published to the live workspace
which leads to large numbers of cache tags that will be flushed.

The messages stored with individual content cache tags
take up a lot of unnecessary memory in production
context and not are even used there.

With this change the behaviour can be enabled via
the setting `Neos.Neos.fusion.contentCacheDebugMode`.

This helps when trying to use AOP to influence caching behaviour.
The RouteCacheFlusher does it the same way.

This can speed up flushes after publishing a lot if a lot of document nodes
are affected by the published changes.

Co-authored-by: Karsten Dambekalns <karsten@dambekalns.de>