Add newrelic implementation

[DarkoKukovec]

Summary

Task:

https://app.productive.io/1-infinum/tasks/3675565

Associated design:

N/A

Documentation:

https://newrelic.com/blog/how-to-relic/nextjs-monitor-application-data

Description

Add the setup for New Relic monitoring (SSR and Browser)

Checklist:

• Code is linted and prettified before the review
• I have performed a self-review of my code
• Tests pass locally with my changes

[isBatak]

Where can we get the key?
Should this Key be secret?

[DarkoKukovec]

It is generated when you create a project (I plan to write a guide for this part). I need to check if it's also passed to frontend or if it's only used on the backend

[isBatak]

Why is this an array? I'm just curious :d

[DarkoKukovec]

Not sure, this whole file was generated by newrelic

[isBatak]

I think there are some TS helpers for inferring types form getInitialProps so you don't have to maintain it in two places.

[isBatak]

Not two places, maintain it manually when you add another prop to gIP return statement

[isBatak]

Suggested change

	): Promise<DocumentInitialProps & { browserTimingHeader: string }> {
	) {

[isBatak]

You don't need explicit return type

[isBatak]

Suggested change

	const AppDocument = ({ browserTimingHeader }: { browserTimingHeader: string }) => {
	type Props = DocumentProps & Awaited<ReturnType<Awaited<typeof AppDocument.getInitialProps>>>;
	const AppDocument = ({ browserTimingHeader }: Props) => {