Move to pnpm

[NullVoxPopuli]

Builds on top of

• Reduce broccoli usage/move benchmarks to public folder #10
  which builds on top of
  • Move bootstrap from vendor + broccoli to 'just a static file' #9

moving to pnpm is happening because:

1. faster local install
2. I'm going to start extracting packages
   In particular, I want to make the "test client" (test-client.js) stuff all its own package, as well as another package which contains all the component definitions that the different apps will use.
   So, I'm thinking something like:

   packages:
    - '.' # root, current app
    - 'libraries/*'
      # e.g.: test-client, common-components
    - 'app-at-version/*' 
      # e.g.: ember-5.0, ember-5.5, ember-5.10, etc
      #   these apps will depend on both test-client and common-components
      #   and be fully runnable on their own.
      #   The current app would then be an aggregator of the localStorage outputs of each app