First cut at making a release binary

[aiuto]

This PR adds the framework to make a release binary that should be used by any rule set that just wants to declare a license. As such, the package does not depend on any other rules.

This is the first of several PRs which will bootstrap a steady state.

• this PR
• cut a release
• update rules_pkg to use the release
• cut a rules_pkg release
• verify we can depend on each other correctly in this embrace
• vendor this package to bazelbuild/bazel
• produce compliance report showing rules_pkg licensing
• iterate through other repositories.

[danielmachlab]

Hi Tony, these changes look good to me.

I tested out the change by pulling the branch and building the new targets. I also took the rules_license-0.0.1.tar.gz produced by bazel build distro:distro and used it in one of my example projects that uses rules_license for licensing. Everything worked as expected.