Report empty repos & repos with only a README

[zkoppert]

Is your feature request related to a problem?

From a GitHub Enterprise customer:

We are trying to do some searches and wondering if you have code that would search our repos for repos without any files or that only have a README.md file.

This action would be in the same category as the github/stale-repos action where the goal is to keep an organization well maintained by identifying repositories that potentially shouldn't be there/aren't useful.