This will ensure that we do not break anyone who has adopted APIs like
CheckedContinuation.resume that now have sending parameters.
An example of where this can come up is shown by the ProcessType in SwiftToolsCore:
```swift
@available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
@discardableResult
public func waitUntilExit() async throws -> ProcessResult {
try await withCheckedThrowingContinuation { continuation in
DispatchQueue.processConcurrent.async {
self.waitUntilExit(continuation.resume(with:))
}
}
}
```
This fails to compile since self.waitUntilExit doesn't expect a function that
takes a sending parameter. We want to give people time to fix such issues.
This is important since the witness is not promising to return a disconnected
value and the caller of the requirement is going to accept that.
rdar://127675288
