[Deliverable] Implement and integrate libp2p mix in js-waku for light push

[chair28980]

Owner: Core Research

Feature: Mix

FURPS:

P1. Payloads are limited to 4kB

S3. Browser based apps built using js-waku support acting as entry nodes.

Checklist:

• Specs: link to specs
• Code: link to GitHub issues/PRs/Epic
• Dogfood: link to dogfooding session/artefact
• Docs: links to README.md or docs.waku.org (TBD)