[do not merge] major refactor of downloads, environment creation

[bollwyvl]

As a prelude to #75/#76, we talked about splitting out the downloader pieces into smaller things.

This is that... and entirely too much else. I basically couldn't track where all the if statements were going, and this is what I came up with to make future providers of installers more tractable... micromamba wouldn't look like what's in there, but we'll get there when we get there, I guess.

• move most of the validation to parse time to fail earlier
  • more can be done here
• strategy pattern (one per very short file, except miniconda download) applied to:
  • installers sources
  • base tools (e.g. mamba, conda-build)
  • environment creation
  • baseline packages (e.g. python, though now can add more)
• does at most one solve, seems quite snappy
• more consistent top-level logging approach
• standardized most functions to take...
  • a frozen inputs (as from the yaml, this could still be improved
  • a dynamic grab-bag of things (e.g. useMamba, the parsed env file)
    • some more typing could be applied here
• normalize package spec string creation
• removed most of the any types
• removed the (Error|Success)Result pattern, leaning almost entirely on throw and one top-level catch (except around settings)

Anyhow... I would worry about this bitrotting pretty fast, as any other features/fixes change, but it's also going to be a bear to review. So sorry! I can try to pull it apart into smaller incremental pieces, but basically did the whole thing in one go when my network was patchy.

Sub-PR Plan

• [1 of #107] Split up setup.ts #108 get to this basic file structure (no subdirectories) without changing any code so subsequent prs are targeted at individual files, and not just looking at the "god" function
  • by-the-by: will probably set .gitattributes for dist to be binary... it's never worth reviewing
• [2 of #107] Use native Error #109 refactor Result to native throw
• [3 of #107] Refactor input parsing #123 refactor the input parsing,
• [wip] [5 of #107] add dynamic options #125 use inputs throughout (along with the mutable state object)
• [6 of #107] move installer detection logic to implementation #126 refactor the installer provider
• [7 of #107] expand env parsing and command creation  #127 refactor the env provider
• refactor the tool provider

[goanpeca]

Hi @bollwyvl as always thanks for this. This is a bit too much for a single PR so if we could split this, that would be great. Also less chance of breaking things.

Question what is the deal with underscored files?

[bollwyvl]

Question what is the deal with underscored files?

Just for sorting. could be changed.

too much for a single PR

Sure, fair. Will add a top-level plan of action...