Defer generic awaited type

[Jack Bates (jablko)]

async function f<T>(x: T) {
    return x;
}
const result: Promise<number> = f(undefined as Promise<number>);

Before

!!! error TS2322: Type 'Promise<Promise<number>>' is not assignable to type 'Promise<number>'.
!!! error TS2322:   Type 'Promise<number>' is not assignable to type 'number'.

After

getConditionalType() defers the awaited type until the generic type is instantiated, if it might or might not be promise like.

Fixes #27711

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[TypeScript Bot (typescript-bot)]

The TypeScript team hasn't accepted the linked issue #27711. If you can get it accepted, this PR will have a better chance of being reviewed.