Do not list apps which do not have a release for a supported Nextcloud version

[jancborchardt]

Some outdated apps like https://apps.nextcloud.com/apps/direct_menu (sorry @juliushaertl ;D) are still listed very prominently in the app store even though they only support Nextcloud 10 or up til 11 which is not supported anymore.

These apps should not be shown in the appstore web interface. As discussed with @MorrisJobke @juliushaertl

[BernhardPosselt]

Should probably be combined with #412

Add the filter and select the latest Nextcloud version by default.

[jancborchardt]

I'd say filter is more advanced and less necessary. When you are in your Nextcloud app mgmt, it already filters. But the app web interface is a showcase – and that should only show maintained stuff.