Internally a data source read is represented as a creation diff for the
resource, but in the UI we'll show it as a distinct icon and color so that
the user can more easily understand that these operations won't affect
any real infrastructure.
Unfortunately by the time we get to formatting the plan in the UI we
only have the resource names to work with, and can't get at the original
resource mode. Thus we're forced to infer the resource mode by exploiting
knowledge of the naming scheme.
New resources logically don't have "old values" for their attributes, so
showing them as updates from the empty string is misleading and confusing.
Instead, we'll skip showing the old value in a creation diff.
Sometimes in all the output from ```terraform plan```, it is difficult
to see the ```(forces new resource)``` message.
This patch adds a little bit of color.
Martin Atkins