The great refactor

This MR lands a huge breaking change refactor to the project.

• Adds a new ape_cosmos_lock rule to scrape and generate integrities for each cosmos.zip binary
• Implements a new ape_cosmos extension to read the lock file and generate the download repositories
  • Keeps old download versions available for use downstream if users need to pin to a particular version
  • Allows downstream to add new lockfiles/binaries into the extension for download
  • Generates the upload targets automatically for easy mirroring of binaries
  • Repositories can be imported directly from the extension rather than toolchain_export
• Implements actual tests for some binaries. Most are not implemented, see #7
• Removes the legacy ape_binary rule
• Removes the deprecated @ape//:* targets

In general this gets the project into a state where it is much easier to maintain. This leads us close to 1.0.0.

Fixes #4 (closed)