Better typing for exactOptionalPropertyTypes needed

[HolgerJeromin]

I did not find a "planning" issue in this or TS repository.
All types from this repository should be safe to use with the new Typescript option.

Got this error but I am quite sure this is a problem with many definitions:

            let IntlOptions: Intl.DateTimeFormatOptions = {
                timeZone: undefined
            };

ref #1092

[saschanaz]

Intl APIs are from ECMAScript spec and bugs about it should go TypeScript repo instead.