BUGFIX: Store cache content in BLOB field with PdoBackend
BUGFIX: Store cache content in BLOB field with PdoBackend

The cache PdoBackend used a MEDIUMTEXT column for the content, with
some special handling for PostgreSQL to fix null bytes in the content.

When using igbinary, even with MariadDB problems can occur, since the
written content is garbled when fetched back and cannot be unserialized
anymore, leading to cache misses / read errors.

This change fixes it by using a MEDIUMBLOB / BYTEA field for the
content.

neos/flow,neos/flow,neos/flow,neos/flow