This PR makes some improvements to the documentation. It migrates
docker, debugging, and chrome extension documentation to the `guides`
folder and also updates some of the terminology.
This PR moves the puppeteer source code into separate mono-repo packages:
- `puppeteer` and `puppeteer-core` are now separated into their own
packages.
- `puppeteer-core` has a new exports called `puppeteer-core/internal`
for internal usage.
Tests and various tools have been updated to accommodate the migration.
This PR removes the manual vendoring process. Third party code can now
be updated using the typical NPM pipeline with types/code bundling done
through Rollup.
