Common properties check:Fix intersection-parent check

[sandersn]

The check for common properties ("weak type check") when the target is an intersection is supposed to skip the common property check for constituents and instead check assignability of properties for the entire type. The current code correctly skips the check for constituents, but fails to check the whole intersection sometimes. That's because the whole-intersection check uses isPerformingCommonPropertyChecks, but that reports the state of the intersection itself, not its constituents.

This PR changes the boolean flag isApparentIntersectionConstituent to a box, { skipped: boolean }, that lets children report whether they skipped the common property check or not.

The meat of the PR is in the first page or so; everything else is just changing the type of isApparentIntersection.

This PR is not done:

1. I'm not sure this approach is correct. It might be better to always run the whole-intersection property check, even when no constituent is weak.
2. I haven't cleaned up the parameter-passing code; in particular, I didn't introduce a type alias for the result box, and most calls create a box and then don't look at the result.
3. The new, weaker isPerformingExcessPropertyChecks and isPerformingCommonPropertyChecks need to be checked with !isApparentIntersection, but probably not everywhere.

And I don't attempt to fix known problems with the existing approach, like the caching problem or the fact that source intersections also have their children skip common property checks.

Fixes #33944

[sandersn]

I'd like some commentary from others on the approach before I clean this up.

[sandersn]

I updated a failing baseline, which I believe is correct. I can't tell if it's desirable but I suspect not:

export function myHigherOrderComponent<P>(Inner: React.ComponentClass<P & {name: string}>, props: Readonly<P>) {
    <Inner {...props} name="Matt"/>;
     ~~~~~
!!! error TS2326: Types of property 'name' are incompatible.
!!! error TS2326:   Type '"Matt"' is not assignable to type 'P["name"] & string'.
!!! error TS2326:     Type '"Matt"' is not assignable to type 'P["name"]'.
}

The error comes from assigning

Readonly<P> & { name: "Matt" }

   ==>

IntrinsicAttributes 
& IntrinsicClassAttributes<Component<P & { name: string; }, any, any>> 
& Readonly<{ children?: ReactNode }> 
& Readonly<P & { name: string }>

Previously the common property check was skipped, correctly, for all constituents of the target. The whole-intersection check was also skipped, incorrectly, since the whole intersection was not a weak type because of { name: string }.

However, now that the constituents record when they skip a common property check, the whole-intersection check runs and checks that the four properties of the target are assignable from the source. This is true for key,ref,children, but not for name, which has type "Matt" in the source but (P & { name: string })['name'] in the target.

As far as I can tell, this hole is required for React HOCs to compile, because the error seems correct to me.
Edit: Well, except that Readonly<P & { name: "Matt" } is assignable to Readonly<P & { name: string }>. So maybe the whole-intersection check just needs to cover more of assignability than just propertiesRelatedTo.

[sandersn]

#34789 is a better fix

[weswigham]

@sandersn should this be closed now?