[API Required] Options to select hypervisors should be filtered in the dropdown based on Platform

[mohitsuman]

This case is specific to download and running minishift from the extension.

Scenario: I think the option to specify the virtualization should be filtered out based on platform
say if i m on mac, list of supported hypervisors should only be shown. Because if anything else is mentioned, it will fail the minishift runtime and then it has to be removed from the list of servers and again downloaded, which means going through the list of steps.

Adding only the required list in the dropdown will help increase the overall experience.

[robstryker]

WorkflowResponseItem has the notion of validResponses, a string list which can be shown in quickpicks for a given field.

Unfortunately, the create-server workflow's data object is Attribute and does not have this. This would require an API enhancement in rsp-server. We can look into it.