feat: add offline/online events

[JCB-K]

What:

Added support for the offline and online event to fireEvent.

Why:

To test code that listens for the events.

How:

added events to event-map.js

Checklist:

• [ ] Documentation added to the docs site N/A
• [x] Tests
• [x] TypeScript definitions updated
• [x] Ready to be merged

This is my first contribution so I'm unsure if I did it all right, feel free to provide candid feedback!

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Codecov Report

Merging #1205 (86405b8) into main (9f363af) will not change coverage. The diff coverage is n/a.

@@            Coverage Diff            @@
##              main     #1205   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           24        24           
  Lines          998       998           
  Branches       327       327           
=========================================
  Hits           998       998           

Flag	Coverage Δ
node-12	100.00% <ø> (ø)
node-14	100.00% <ø> (ø)
node-16	100.00% <ø> (ø)

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Impacted Files	Coverage Δ
src/event-map.js	100.00% <ø> (ø)

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[JCB-K]

@eps1lon done! I assumed they were inferred from events-map.js :)