This is a continuation of #17058 after we've shipped the embedded snapshot. Opening a new issue since most of the discussions in the original one have been settled, and now we are focusing on:

1. Moving more of the bootstrap into the embedded snapshot
2. Enabling user land snapshot

For discussions about technical details, please use the design doc: https://docs.google.com/document/u/1/d/15bu038I36oILq5t4Qju1sS2nKudVB6NSGWz00oD48Q8/edit?usp=sharing This issue is opened for tracking.