[BUGFIX] Use BLOB type column for ses_data in be_sessions table

The unified session handling for frontend and backend requires
identical SQL column types to properly escape the input data.
Using binary encoding for session data in combination with a TEXT
type field in the BE fails on PostgreSQL.

Change-Id: I3f3f379b43f873335207232e498f2e9e2c8b35e5
Resolves: #79324
Releases: master
Reviewed-on: https://review.typo3.org/51314


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Manuel Selbach <manuel_selbach@yahoo.de>
Tested-by: Manuel Selbach <manuel_selbach@yahoo.de>
Reviewed-by: Markus Klein <markus.klein@typo3.org>
Tested-by: Markus Klein <markus.klein@typo3.org>