Make the capabilities manager strict
Make the capabilities manager strict

* Add return types
* Add scalar type hints
* Use [] instead of array_push (PHPStromg inspection recommendation)

Signed-off-by: Roeland Jago Douma <982d370f7dc34a05b4abe8788f899578d515262d@famdouma.nl>

michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,michaelletzgus/nextcloud-server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server,nextcloud/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,andreas-p/nextcloud-server