Improve generic function inference

[ahejlsberg]

This PR addresses several issues related to type inference involving combinations of contextually typed arrow functions and generic functions.

In general, type argument inference defers processing of contextually typed arrow functions and function expressions as long as possible such that inferences can be collected from other arguments before those inferences are fixed and used to type the arrow function or function expression parameters. For example:

declare function invoke<T, U>(f: (x: T, y: T) => U, x: T, y: T): U;
let thirty = invoke((x, y) => x + y, 10, 20);

Here, we defer processing of the arrow function until we have made inferences the two number arguments and then use those inferences to assign type number to x and y.

Previously, contextually typed arrow functions and function expressions were the only types of arguments for which we'd defer inference. However, arguments with generic function types are also be subject to contextual typing. Consider:

declare function pipe<A extends any[], B, C>(ab: (...args: A) => B, bc: (b: B) => C): (...args: A) => C;
declare function identity<T>(x: T): T;
declare function list<T>(x: T): T[];
declare function box<V>(x: V): { value: V };

const f1: <T>(x: T) => { value: T[] } = pipe(list, box);  // Ok
const f2: <T>(x: T) => { value: T[] } = pipe(x => [x], box);  // Was error, now ok
const f3: <T>(x: T) => { value: T[][] } = pipe(x => [x], pipe(x => [x], box));  // Was error, now ok

Before this PR we would error on f2 because we'd process the box argument ahead of the x => [x] argument and miss the opportunity to have inferences flow from the return type annotation into A and from the result of x => [x] into B before using inferences for B to contextually type box. Likewise, we'd error on f3 because we'd process the inner pipe call before the x => [x] arrow function.

With this PR we now defer processing of arguments having generic function types along with contextually typed arrow functions and function expressions.

Fixes #25791.
Fixes #25826.

[weswigham]

This line seems like a typo.

[ahejlsberg]

I just wanted to be extra sure!

[DanielRosenwasser]

I heard this is how you make really really thread-safe code in Node dot jay ess.