Make dry run log output more accurate

[briskt]

Adapter create, update, delete support, or lack thereof, is not reflected in the dry run mode log output. Would be beneficial to have an adapter function that can be called to get the details of what is supported so the output can reflect that. Alternatively, the adapter ApplyChangeSet function could be called with a parameter to disable API writes.

For example, the Google Users adapter does not currently support deletes, but the dry run log shows that deletes would be performed.