Add functionality to execute Resolver without Diagnosis.

[andrewnguonly]

Summary

In rare cases, the behavior of an IHealthPolicy should be overridden. In such a case, an outside system or human operator must take action. This pull request provides an interface so that outside systems may execute Resolvers without Diagnosis, effectively overriding the behavior of the IHealthPolicy.

Implementation

1. Add method resolve to IResolver interface. Unimplemented.
2. Add method executeResolver to IHealthPolicy interface. Unimplemented.
3. Override executeResolver method in HealthPolicyImpl class.
4. Fixed minor spelling error: hanlder -> handler.

[msftclas]

All CLA requirements met.