[v8] Allow setting the route destination port via the CF CLI map-route command

[sethboyles]

Thank you for contributing to the CF CLI! Please read the following:

v8 port of #3612

Note: Please create separate PR for every branch (main and v8) as needed.

Description of the Change

This PR introduces support for setting the route destination port via the CF CLI map-route command using a new app-port parameter. This functionality is comparable to the existing app-protocol parameter used for setting the destination protocol.
The change enables users to specify the destination port directly when mapping a route to an application.

Why Is This PR Valuable?

This change improves the flexibility of the map-route command by allowing users to configure the destination port for their routes directly from the CLI. This is particularly valuable for applications that require traffic to be routed to specific, non-default ports, aligning the CLI's capabilities with the underlying networking features.
Especially this is useful for docker apps that have multiple ports, where the end user needs to switch tools to configure it via API oder Terraform instead of just using cf push from the command line as long as the CLI and the manifest do not support setting it.

Applicable Issues

https://github.com/cloudfoundry/cli/issues/3613

How Urgent Is The Change?

Not urgent

Other Relevant Parties

Who else is affected by the change?