Add missing dependencies entry for which, which was causing the wrong version of which to be used, which caused R not to load on some configurations of Windows

[softwarenerd]

This PR addresses #4280.

This issue was tracked down to the fact that the positron-r extension did not have an explicit dependencies entry for the which package, but it did have a devDependencies entry for @types/which ("@types/which": "^3.0.0",).

As a result of this, the positron-r/node_modules folder contained which 2.0.2 (I believe) from:

mocha@^9.2.1:
  version "9.2.2"
  resolved "https://registry.npmjs.org/mocha/-/mocha-9.2.2.tgz"
  integrity sha512-L6XC3EdwT6YrIk0yXpavvLkn8h+EU+Y5UcCHKECyMbdUIxyMuZj4bX4U9e1nvnvUUvQVsV2VHQr5zLdcUkhW/g==
  dependencies:
    "@ungap/promise-all-settled" "1.1.2"
    ansi-colors "4.1.1"
    browser-stdout "1.3.1"
    chokidar "3.5.3"
    debug "4.3.3"
    diff "5.0.0"
    escape-string-regexp "4.0.0"
    find-up "5.0.0"
    glob "7.2.0"
    growl "1.10.5"
    he "1.2.0"
    js-yaml "4.1.0"
    log-symbols "4.1.0"
    minimatch "4.2.1"
    ms "2.1.3"
    nanoid "3.3.1"
    serialize-javascript "6.0.0"
    strip-json-comments "3.1.1"
    supports-color "8.1.1"
    which "2.0.2"
    workerpool "6.2.0"
    yargs "16.2.0"
    yargs-parser "20.2.4"
    yargs-unparser "2.0.0"

This version of which does not support the nothrow option for async which, which we rely on in this code fragment from extensions/positron-r/src/provider.ts:

	const whichR = await which('R', { nothrow: true }) as string;

Because of this, on some configurations of Windows, an error was being thrown which caused R not to load.

For background on this, see: npm/node-which#80. This was the exact same problem.

QA Notes

[jennybc]

So happy we ran this down!

Works fine for me in my Windows VM (where I could never reproduce this), so that's good.

And it just plain makes sense.

[jennybc]

Nit: it feels like we're keeping these in alphabetical order? In which case we should:

Suggested change

	"winreg": "^1.2.5",
	"which": "^3.0.0"
	"which": "^3.0.0",
	"winreg": "^1.2.5"

[softwarenerd]

Spot on. Fixed.

[jennybc]

🎉