add reason to CfnNotStabilizedException

[cortez7]

The current stabilization error message "Resource of type '%s' with identifier '%s' did not stabilize." lacks a reason so users may not be able to determine the cause of the stabilization error.

Changes

• add reason argument to CfnNotStabilizedException constructors with documentation
• update the corresponding NOT_STABILIZED exception message
• deprecate the old constructors

Testing

• added unit tests for new constructors

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.