[1 of #107] Split up setup.ts

[bollwyvl]

The setup.ts file is getting unwieldy. To make future PRs more easily reviewed, this PR will break it up into some smaller files.

• first part of [do not merge] major refactor of downloads, environment creation #107
• marks all js as binary, as nobody reviews them anyway
• runs linter against cron stuff
• rebuilds because 🤷
• break up existing constants, functions, and types into smaller files
  • won't touch setupMiniconda

[goanpeca]

@bollwyvl could you rebase. Then we should be good to go and iterate.

[goanpeca]

Any comments @conda-incubator/setup-miniconda-team ? :)