Support "ports" application attribute via update

[GFriedrich]

Currently one can only set the "ports" attribute via CreateApplicationRequest.
It's neither possible to use UpdateApplicationRequest to update the ports nor to hand over the ports via the ApplicationManifest e.g. when using the PushApplicationManifestRequest.
Would be awesome if that could be added.
Thanks in advance!

[GFriedrich]

@twoseat Do you have any objections if I open a PR for this?

[twoseat]

No objection at all!

[twoseat]

Reopened after discussion on planned CAPI changes

[GFriedrich]

The scope of this issue has been reduced to adding the app ports only to the update of an application until the usage of app ports within the app manifest has been clarified.