Missing reviews for some create fixes

[FMorschel]

While working on #61186 I noticed some things:

1. Missing create method "method" quick fix when the class is defined in another part file #60472 is missing some test cases (might be working but I've not manually tested either):

• Method/function (tear-offs)
• Operators
• Extension members

2. The following example has no Create extension method case:

class A<T> {}

T? Function() i<T>(A<T> a) => a.methodTearoff;

And it should have the same priority mentioned at this comment (before getters).

FYI @bwilkerson