Issue: #1313
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**What kind of change does this PR introduce?**
Feature.
**Did you add tests for your changes?**
Yes.
**If relevant, did you update the documentation?**
Yes.
**Summary**
Supports keyboard shotcuts on MacOS. See Chrome Devtools Protocol
document:
https://chromedevtools.github.io/devtools-protocol/tot/Input/#method-dispatchKeyEvent.
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.
