Add an overloaded `ConfigDataEnvironmentPostProcessor.applyTo` method
that accepts a listener that can used to track the updates that were
applied to the `Environment`.

The listener can be used to track the which `ConfigDataLocation` and
the `ConfigDataResource` were used to add a `PropertySource`. The lister
can also be used to tell which profiles were applied.

This enhancement is being added in a patch release because it's will
be useful for Spring Cloud 2020.0.0.

Closes gh-24504