Use nodejs 16 versions of yarn and pnpm

[Rheeseyb]

Problem:
Yarn and PNPM use their own version of nodejs, meaning we weren't actually using node.js 16 when we thought we were, breaking the build after updating vs code

Fix:
Update the shell.nix to use the node.js 16 versions of yarn and pnpm. Unfortunately due to a strange bug (see NixOS/nixpkgs#145432), the pkgs.nodePackages_latest versions of these don't result in a symlink, so we had to manually create those, which also meant copying an override from nix's node-packages/default.nix for pnpm and pnpx.

Output:

$ yarn config list
yarn config v1.22.11
info yarn config
{
  'version-tag-prefix': 'v',
  'version-git-tag': true,
  'version-commit-hooks': true,
  'version-git-sign': false,
  'version-git-message': 'v%s',
  'init-version': '1.0.0',
  'init-license': 'MIT',
  'save-prefix': '^',
  'bin-links': true,
  'ignore-scripts': false,
  'ignore-optional': false,
  registry: 'https://registry.yarnpkg.com',
  'strict-ssl': false,
  'user-agent': 'yarn/1.22.11 npm/? node/v16.6.2 linux x64',
  lastUpdateCheck: 1636544518023
}
info npm config
{
  'cache-min': '9999999',
  'strict-ssl': true
}
Done in 0.04s.

$ pnpm config list
; "user" config from /home/rheese/.npmrc

cache-min = 9999999 
strict-ssl = true 

; node bin location = /nix/store/hs9ajfsbjybx4mf1f35xpj1nbdfj5hhz-nodejs-16.6.2/bin/node
; cwd = /home/rheese/Workspace/Utopia/utopia
; HOME = /home/rheese
; Run `npm config ls -l` to show all defaults.

[relativeci]

Job #402: Bundle Size — 42.81MB (~-0.01%).

aab0e7a vs 57ffdcc83116a21e7b1728916d1f52e78a90d8d8

Changed metrics (1/8)

Metric	Current	Baseline
Initial JS	27.72MB(~-0.01%)	27.72MB

Changed assets by type (1/7)

	Current	Baseline
JS	42.8MB (~-0.01%)	42.8MB

---

View Job #402 report on app.relative-ci.com

[github-actions]

Link to test editor
This PR:
Scroll Canvas: 58.4ms (43.7-154.6ms) | Resize: 95.3ms (20.4-236.9ms) | Selection: 271.1ms (232.9-634.2ms) | Calc Pi: 29ms (27-43ms) | Empty Dispatch: 49.7ms (40.1-128.9ms) |
Compare with last deployed Master:
Scroll Canvas: 57.5ms (42.1-110.9ms) | Resize: 89.2ms (18.6-257.2ms) | Selection: 271.3ms (238.8-731.6ms) | Calc Pi: 29ms (27-38ms) | Empty Dispatch: 48.3ms (41.2-207.3ms) |

[github-actions]

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This PR:
Scroll Canvas: 73.5ms (53.4-173.1ms) | Resize: 120.7ms (19.7-982.2ms) | Selection: 351.1ms (291.5-838.1ms) | Calc Pi: 27ms (26-44ms) | Empty Dispatch: 55.9ms (45.8-681ms) |
Compare with last deployed Master:
Scroll Canvas: 76.4ms (59.5-117.6ms) | Resize: 120.2ms (27.7-263.1ms) | Selection: 352.9ms (303.7-621.1ms) | Calc Pi: 28ms (26-35ms) | Empty Dispatch: 55.9ms (46.5-162.6ms) |

[github-actions]

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This PR:
Scroll Canvas: 80.5ms (57.3-148ms) | Resize: 127.4ms (22.9-265.7ms) | Selection: 352.2ms (295.7-626.5ms) | Calc Pi: 41ms (37-90ms) | Empty Dispatch: 64.5ms (48.3-784.4ms) |
Compare with last deployed Master:
Scroll Canvas: 86.8ms (56.7-535ms) | Resize: 120.8ms (27.7-313.3ms) | Selection: 358.8ms (285.3-994.3ms) | Calc Pi: 39ms (35-50ms) | Empty Dispatch: 61.5ms (44.7-582.3ms) |

[github-actions]

Link to test editor
This PR:
Scroll Canvas: 78.7ms (58-177.5ms) | Resize: 128.9ms (25.4-321.6ms) | Selection: 522.6ms (412.7-760ms) | Calc Pi: 30ms (29-49ms) | Empty Dispatch: 64.9ms (49.1-699.9ms) |
Compare with last deployed Master:
Scroll Canvas: 75.7ms (54-136.3ms) | Resize: 131.8ms (30.7-280.3ms) | Selection: 363.9ms (303.9-871.2ms) | Calc Pi: 33ms (29-108ms) | Empty Dispatch: 66.3ms (49.6-395.2ms) |