[Bug]: __dirname points to root

[codydaig]

Bug description

Steps to reproduce the problem:

1. In a project that uses webpack and typescript, depending on configuration of other node/webpack items, __dirname points to /. This results in a TypeError tracing back to the Browser Launch.

Further investigations show that initializePuppeteerNode isn't setting puppeteerRootDirectory.

The fix for this is to fall back to process.cwd() when pkgDir.sync(__dirname) comes back undefined.

Puppeteer version

13.1.2

Node.js version

14.18.0 & 16

npm version

6.14.15

What operating system are you seeing the problem on?

Linux, macOS, Windows

Relevant log output

TypeError [ERR_INVALID_ARG_TYPE]: The "path" argument must be of type string. Received null
     at new NodeError (internal/errors.js:322:7)
     at validateString (internal/validators.js:124:11)
     at Object.join (path.js:1148:7)
     at new BrowserFetcher (webpack:////Users/codydaig/dev/opensource/puppeteer/lib/cjs/puppeteer/node/BrowserFetcher.js?:162:22)
     at resolveExecutablePath (webpack:////Users/codydaig/dev/opensource/puppeteer/lib/cjs/puppeteer/node/Launcher.js?:610:28)
     at ChromeLauncher.launch (webpack:////Users/codydaig/dev/opensource/puppeteer/lib/cjs/puppeteer/node/Launcher.js?:107:57) {
   code: 'ERR_INVALID_ARG_TYPE'
 }

[OrKoN]

This should be solved via #8003