Update intent methods to use AppIdentifier type

[nkolba]

• [x] raiseIntent - signature
• [x] raiseIntentForContext - signature
• [ ] route to instance if an instance identifier is provided
• [ ] deprecate old signatures

Ensure proper error is thrown if target instance is specified but not found:

If a specific target app parameter was set, but either the app or app instance is not available then the ResolveError.TargetAppUnavailable or ResolveError.TargetInstanceUnavailable errors MUST be returned.

[nkolba]

most of this is addressed with PR #82 . Will need to verify the routing with instance identifier arg.