failing resource poisons the context/flush implementation

[DavidS]

Describe the Bug

When puppet applies two resources of the same type, and the first one fails, but the second one would succeed, the lack of a reset of the context.failed? status in resource_api.rb:388 causes the second resource to fail too.

Expected Behavior

The second resource should be evaluated independently of the first resource's success.

Additional Context

Originally filed as https://tickets.puppetlabs.com/browse/PDK-1134