Add flag for --workload-state when installing/update workloads for the old install behavior

[marcpopMSFT]

dotnet workload update --workload-state global state saved into programdata on whether to use workload sets or not

[marcpopMSFT]

@baronfel we need to confirm the parameter name here

[baronfel]

The flag we use should be --mode, and it should have

• auto,
• workloadSet, and
• looseManifest options

For the initial release, auto will default to looseManifest. Once we have a certain amount of stability/feedback/confidence in the mechanism, auto's semantics can be changed to workloadSet.