[FEATURE] Integrate preliminary PackageManager API

The Package Manager from Flow has been backported and integrated as
CMS Package Manager. This enables us to use full vendor namespaces for
extensions and brings us closer to a unified TYPO3 package format.

For more Details see: http://wiki.typo3.org/Blueprints/Packagemanager

Resolves: #47018
Releases: 6.2
Change-Id: I52abedaf470cebddb3553e37581021bf368380e6
Reviewed-on: https://review.typo3.org/19605
Reviewed-by: Christian Kuhn
Tested-by: Christian Kuhn
Reviewed-by: Alexander Opitz
Reviewed-by: Sascha Egerer
Reviewed-by: Thomas Maroschik
Tested-by: Thomas Maroschik
Tested-by: Alexander Opitz
Reviewed-by: Ernesto Baschny
Tested-by: Ernesto Baschny