Prepare for homebrew migration of toolchain

What does this MR do?

• Restore running specs for snapshotted images, to make sure our specs keep working on old images. Fix the failing tests.
• Refactor ruby/python/node packages version data to prepare for using gem, pip and npm ourselves
• Add htop/awscli and update asdf to 0.8.1
• Move package specs from {asfd,homebrew}_spec.rb to packages_spec.rb

Why was this MR needed?

In a following MR, I will move our dependencies from asdf to brew. This is the preparatory work to make that MR smaller.

What's the best way to test this MR?

What are the relevant issue numbers?