Starting version of website with docs pages and rules

[JoshuaKGoldberg]

PR Checklist

• Addresses an existing issue: fixes Documentation update request #3993 (and will open many more followups)
• That issue was marked as accepting prs
• Steps in CONTRIBUTING.md were taken

Overview

A trimmed down version of @armano2's beautiful #3147, with the website/ directory moved into packages/ for consistency. Builds off the same branch's Git commit history.

In addition to the tasks already mentioned in #3147, we'll need to follow up on at the very least:

• Deploying to Netlify
• Adding back the playground/REPL area
• Audit language, phrasing, flow, etc. of docs
• Reworking the rules page, such as improving the h1 and removing previous/next
• Accessibility/aXe audit
• Automate calling generate-sponsors regularly, such as the way generate-contributors is on a cron
• Fix the warn Docs markdown link couldn't be resolved: warnings
• Investigating moving docs/ files to the packages/website directory (not sure we want to)

I'd additionally like to file followup tasks for:

• Search (Algolia?)
• Adding some kind of easter eggs 😉
• Creating our own theme to stand out
• Requiring issues use the playground if possible 💪

Unless directed otherwise I'll probably play with GitHub projects to set all that up.

[armano2]

website/src/modules and website/src/vendor should be removed

current compile errors has been solved in #4101

[codecov]

Codecov Report

Merging #4099 (0f325fc) into fix-babel-7_16-tests (0cf5ae3) will decrease coverage by 0.38%.
The diff coverage is n/a.

@@                   Coverage Diff                    @@
##           fix-babel-7_16-tests    #4099      +/-   ##
========================================================
- Coverage                 93.11%   92.73%   -0.39%     
========================================================
  Files                       174      334     +160     
  Lines                      9619    11494    +1875     
  Branches                   3004     3270     +266     
========================================================
+ Hits                       8957    10659    +1702     
- Misses                      248      362     +114     
- Partials                    414      473      +59     

Flag	Coverage Δ
unittest	92.73% <ø> (-0.39%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...perimental-utils/src/ts-eslint-scope/Referencer.ts	100.00% <0.00%> (ø)
packages/scope-manager/src/lib/esnext.bigint.ts	100.00% <0.00%> (ø)
...kages/scope-manager/src/lib/es2017.sharedmemory.ts	100.00% <0.00%> (ø)
packages/scope-manager/src/referencer/index.ts	100.00% <0.00%> (ø)
...ackages/experimental-utils/src/ts-eslint/ESLint.ts	50.00% <0.00%> (ø)
packages/scope-manager/src/lib/es2018.promise.ts	100.00% <0.00%> (ø)
packages/scope-manager/src/lib/es2017.intl.ts	100.00% <0.00%> (ø)
packages/scope-manager/src/lib/es2019.symbol.ts	100.00% <0.00%> (ø)
...-utils/src/ast-utils/eslint-utils/scopeAnalysis.ts	100.00% <0.00%> (ø)
packages/scope-manager/src/lib/esnext.symbol.ts	100.00% <0.00%> (ø)
... and 150 more

Addressed feedback - would love another review please!