* chore: Use devtools-protocol package
Rather than maintain our own protocol we can instead use the devtools-protocol package and pin it to the version of Chromium that Puppeteer is shipping with.
The only changes are naming changes between the bespoke protocol that Puppeteer created and the devtools-protocol one.
This is part of the effort to remove `Events.ts` in favour of defining
events next to the class that emits them. In this case these events are
internal, so there's no docs changes, but it's still worth doing such
that we can remove the Events.ts file in the long term once all the
different events are migrated.
These files will be used by both the web and node versions of Puppeteer.
Another name for this might be "core" but I don't want to cause
confusion with the puppeteer-core package that we publish at the moment.
