Automatically implement LocatableResource for resources that are location scoped within a subscription

[matthchr]

Describe the current behavior
ResourceGroup is the only resource we support that has this pattern, and it's not autogenerated.

Describe the improvement
If/when we want to support autogenerating other location scoped resources (they're not that common) we will need to automatically implement this interface on those resources.

[matthchr]

We should still do this, but not a high priority currently as there just aren't very many of these

[theunrepentantgeek]

Still something we want to do, even though we are now autogenerating ResourceGroup.

[matthchr]

No change from @theunrepentantgeek's status above. Still interested in this

[matthchr]

Not a lot of need for this yet, but still nice to do.

[theunrepentantgeek]

We still want this, given time.