[TASK] Use secure deserialization in extension manager

In order to harden the deserialization of scalar and array values
in extension manager unserialize() calls are hardened further to
disallow object reconstitution. The information is retrieved from
the TYPO3 extension repository (TER) where according countermeasures
are in place to protect object injections - that's why this change
is considered as hardening and not as security issue.

Resolves: #85466
Releases: master, 8.7
Change-Id: I65b61d61e08d0c50b27ae9102d7ba4c4518a8788
Reviewed-on: https://review.typo3.org/57458


Reviewed-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: Andreas Fernandez <a.fernandez@scripting-base.de>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Daniel Goerz <ervaude@gmail.com>
Tested-by: Daniel Goerz <ervaude@gmail.com>
Reviewed-by: Joerg Boesche <typo3@joergboesche.de>
Reviewed-by: Tymoteusz Motylewski <t.motylewski@gmail.com>
Tested-by: Tymoteusz Motylewski <t.motylewski@gmail.com>