v3 API does not allow to specify ports on an app's processes #4079

Issue

With the v2 API, you could assign ports to your app's processes. This was required e.g. if you want to enable traffic to sidecars. With the v3 API, this seems no longer possible. We should discuss if this is a regression or if the feature was intentionally left out.

Context

The v2 API allows to specify ports on which the app shall listen:
https://v2-apidocs.cloudfoundry.org/apps/updating_an_app.html (see body parameter "ports").
Note that the list of ports is stored in the "processes" table.

The feature is used in the "sidecars" test of the CAPI BARAs suite:
https://github.com/cloudfoundry/capi-bara-tests/blob/f407866fdd668387f1283507f72a89022522586f/baras/sidecars.go#L64

With the v3 API this seems no longer possible. The "apps" and the "processes" resources do not allow to specify ports:
https://v3-apidocs.cloudfoundry.org/version/3.180.0/index.html#apps
https://v3-apidocs.cloudfoundry.org/version/3.180.0/index.html#processes

As part of the CF API v2 End of Life story, we have set up a test landscape where v2 is completely disabled:
https://concourse.app-runtime-interfaces.ci.cloudfoundry.org/teams/capi-team/pipelines/capi/jobs/gyro-exp-tests
Now we are trying to migrate the mentioned "sidecars" test to v3. If opening additional ports shall not be supported in v3, we would have to remove the test.

Steps to Reproduce

N/A

Expected result

N/A

Current result

N/A

Possible Fix

Add parameter to v3 "processes" resource that allows to specify additional ports.