feat: unit testing @waku/core

[weboko]

This is a support request

Problem

We have poor coverage on basic primitives in the code and E2E testing is too heavy to test such small things / changes.
This task should cover reliability improvements delivered so far.

Proposed Solutions

Cover @waku/core with unit tests:

• filter;
• lightPush;
• message;
• metadata;
• store;
• streamManager;
• baseProtocol;
• connectionManager;
• keepAliveManger;

[weboko]

Working on BaseProtocol + LightPush.