Spurious warnings about `noasync` calls in `#expect(throws:)`

[grynspan]

Given the following test function:

@available(*, noasync)
func f() {}

@Test func g() {
  #expect(throws: (any Error).self) {
    f()
  }
}

In Swift 6.2 the compiler emits a warning due to improved typechecking during macro expansion:

⚠️ function 'f' is unavailable from asynchronous contexts; this will be an error in a future Swift language mode

Because the compiler is now inferring the type of the closure passed to #expect(throws:) as async before macro expansion rather than inferring its type (as non-async) after.

[grynspan]

Likely caused by swiftlang/swift#80583. We can work around it by adding hidden overloads of the macros without async.

[grynspan]

Tracked internally as rdar://149299786.