Add Dashboard playwright tests to ensure UI functionality and integration with app host

[joperezr]

As discussed offline, we want to add playwright tests to the dashboard in order to have coverage across different layers. The ones we mentioned we'd want to cover are:

• Mocking Data and looking at UI elements.
• Running Dashboard from the AppHost and doing some tests. This will help validate the protocol of communication between dashboard and apphost.
• End-to-End tests using the workload.

I'm temporarily assigning this to @kvenkatrajan , but please feel free to re-assign as appropriate. (I believe you mentioned @adamint was already looking into some of this?)