zlib-ng: New attempt

[ReillyBrogan]

This is a new attempt at zlib-ng using the approach proposed in getsolus/packages#790

If approved, this will supersede that PR. Note that this PR requires that ferryd be shutdown before the first build and turn back on after the second build. The zlib and zlib-ng package artifacts need to be imported at the SAME time otherwise the build environment will be unable to build zlib.

Summary

• Build zlib-ng in compatibility mode, this is ABI/API compatible with zlib
• Build zlib as transition package

Test Plan

• Installed in a Solus VM. Ensured that the upgrade went off without a hitch and that the system still booted afterwords
• Rebuilt a few packages that depended on zlib. Ensured that they successfully rebuilt and that the resulting artifacts had a dependency on zlib-ng, not zlib.

Checklist

• [x] Package was built and tested against unstable