refactor: use typescript

[Weetbix]

This PR converts the project to typescript with no other functional changes.

It uses the template settings for jest/eslint etc from here: https://github.com/actions/typescript-action

There are some cases which had to be @ts-ignore'd and we can improve later, mainly around remarker usage.

You can see the action working as intended in this PR.

[github-actions]

Overall readability score: 24.55/100 (🟢 +4.13)

File	Readability
README.md	39.85 (🟢 +16.54)

View detailed metrics

🟢 - Shows an increase in readability
🔴 - Shows a decrease in readability

File	Readability	FRE	GF	ARI	CLI	DCRS
README.md	39.85	52.12	13.15	23.6	11.61	6.92
	🟢 +16.54	🟢 +7.3	🟢 +3.29	🟢 +4.9	🟢 +0.18	🟢 +0.72

Averages:

	Readability	FRE	GF	ARI	CLI	DCRS
Average	24.55	16	16.06	17.9	15.05	9.34
	🟢 +4.13	🟢 +1.82	🟢 +0.82	🟢 +1.23	🟢 +0.04	🟢 +0.18

View metric targets

Metric	Range	Ideal score
Flesch Reading Ease	100 (very easy read) to 0 (extremely difficult read)	60
Gunning Fog	6 (very easy read) to 17 (extremely difficult read)	8 or less
Auto. Read. Index	6 (very easy read) to 14 (extremely difficult read)	8 or less
Coleman Liau Index	6 (very easy read) to 17 (extremely difficult read)	8 or less
Dale-Chall Readability	4.9 (very easy read) to 9.9 (extremely difficult read)	6.9 or less

[noon-dawg]

🚀