URL displayed in workload get output doesn't depend directly on any given runtime

[heyjcollins]

Description of problem

Currently, the apps plugin gets the URL for a given workload directly from the knative service. This implementation is brittle (if/when a workload has been deployed to a runtime other than kn, even if a publicly addressable route has been configured, there will be no URL displayed in workload get output).

Proposed solution

Given my workload is running, but not as a knative service and the workload has been configured to respond to public http requests (has an addressable URL)
When I run `tanzu apps workload get` for the workload
Then the publicly addressable URL is included in the command output

Example

<Code snippets that illustrate the when/then blocks>

Describe alternatives you've considered

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Additional context

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