Adds [unit] and [unitDisplay] to NumberFormatOptions

[Kan Adachi (obber)]

Fixes#38012.

Adds the unit and unitDisplay option to NumberFormatOptions in src/lib/es5.d.ts

[Microsoft Contribution License Agreements (msftclas)]

All CLA requirements met.

[Barry May (barrymay)]

This PR is perfectly fine, but while you're at it would be nice to get notation in there too :)

[Ben Scott (BPScott)]

Notation is covered in #37721

[Ben Scott (BPScott)]

Yo Nathan Shively-Sanders (@sandersn), any chance we'd be able to address before beta release in addition to #38013?

I think this needs to be updated to go in es2020.intl.d.ts same as #38013

[Orta Therox (orta)]

Did a read through some of the docs, looks good to me

[Nathan Shively-Sanders (sandersn)]

I'll move this over to es2020.intl.d.ts

[Jonathan Cohen (JonathanDCohen)]

What's going on with this? I'm using Typescript 4.1.3 and still getting an error Argument of type '{ style: string; unit: string; }' is not assignable to parameter of type 'NumberFormatOptions'. Object literal may only specify known properties, and 'unit' does not exist in type 'NumberFormatOptions'.

I'm similarly getting internationalized units by using formatToParts(0).find((part => part.type === 'unit')).value and getting an error This condition will always return 'false' since the types 'NumberFormatPartTypes' and '"unit"' have no overlap.

edit: adding "ES2020" to my "lib" option in my tsconfig fixes the first issue, but the second persists. I checked the definition and sure enough "unit" was missed from potential part types.

Reported in #42004