Add app scope to target object

[linyguo]

Add appScope in target spec to allow configuring application scopes from target.

1. If instance has defined scope, use the scope in instance spec.
2. If instance doesn't have a scope, use the scope defined in target spec. If both are not defined, fall back to the default scope.
3. If both instance and target spec defined a scope, will check if the two fields are equivalent. If not, a warning message will be logged and the scope defined in instance spec will be used.

[msftcoderdjw]

I am OK with this change, but please work with @yanjiaxin534 when remote-agent pr to main, this part may be conflict a lot.