Provide actionable help when get error of "provider not yet registered"

[yugangw-msft]

It is possible the provider commands work with is not yet registered, say acr
2 options:

1. Polish the error and tell users to run az prvoider register. This is xpalt does
2. Auto register it, and output a warning which tells users about this and prepare the command might still fail if the region was not propagated in time

Either way, we need to have a common step to capture the error.

[mayurid]

@yugangw-msft : As discussed we should definitely do #1.
We can discuss #2 with ACR guys as the ARM team's recommendation is to avoid this.

[sajayantony]

We don't this auto register is a good option. Submitting a request on users behalf unintentionally seems wrong. But this applies broadly to the CLI and hence we will probably take your recommendation on this.