Enable provider-level debug logging

[EvanBoyle]

For AWS in particular, it would be nice to have request-level details to debug programs that are taking a long time or appear to be stuck.

In my experience, this indicates that some resource within the cloud control API has a bug (for example returning a retriable 500 error code for an error that should be a 404). Probably the fix for that is something like pulumi/pulumi-aws-native#876

But debugging this category of issue would be easier if we had access to request-level debug logs as described in pulumi/pulumi-aws-native#877