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.
* fix: change injected.ts imports
Not sure why api-extractor generates broken .d.ts
files if the start import is used for Poller and TextContext.
* test: use generated types.d.ts in tsd
