Add tests with JSDOM and jest

[r-n-o]

I found a way to add tests without complicating the build too much. Everything stays in one file, still really easy to grasp. The difference is we have a namespace (TKHQ) where functions can be declared and accessible by tests.

Over time we should move everything to the TKHQ namespace, but I figured we need to start somewhere!

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[socket-security]

New dependencies detected. Learn more about Socket for GitHub ↗︎

Packages	Version	New capabilities	Transitives	Size	Publisher
@babel/preset-env	7.22.20	filesystem, shell, environment	+159	15.1 MB	nicolo-ribaudo
jsdom	22.1.0	network, filesystem, environment	+43	7.2 MB	domenic
@babel/core	7.23.0	filesystem, shell, environment	+52	10.9 MB	nicolo-ribaudo
babel-jest	29.7.0	eval, filesystem, shell, environment	+144	17.7 MB	simenb
@testing-library/dom	9.3.3	eval, environment	+74	6.41 MB	testing-library-bot

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👍 Dependency issues cleared. Learn more about Socket for GitHub ↗︎

This PR previously contained dependency changes with security issues that have been resolved, removed, or ignored.

[emostov]

This is awesome