feat(queryhandler): add built-in pierce handler

[johanbay]

Adds a handler 'pierce' that pierces shadow roots while querying.
Closes #6217.

[php4fan]

Why is this still undocumented??

[joelwhiteswan]

is it possible to get this with xpaths?

[gitressa]

I was also looking for a simple example of tageting the shadow root, and found one by @remcovaes in https://stackoverflow.com/a/76967459:

This issue is solved with P selectors in Puppetteer.

In this case you could use page.click('>>> #my-button'). The >>> Allow you to select stuff in shadowRoots.

I know this issue is old, but I needed this and this issue still pops up on searches.