1. use IAppManager instead of AppManager
2. reduce functions to only filter whats needed (update count vs apps
with updates).
3. do not use legacy OC_App
Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>
`<nextcloud min-version max-version>` is now a required element of the
appinfo for quite a long time. So we can remove the legacy warning from
owncloud times. Its validated with the XSD anyways.
Signed-off-by: Ferdinand Thiessen <opensource@fthiessen.de>