`NonisolatedNonsendingByDefault:migrate` flags `isolated(any)` functions

[mattmassicotte]

Description

The following code is flagged by the migrate facility of NonisolatedNonsendingByDefault, but I do not think it should.

Reproduction

func useNonSendable() {
    acceptSending {
        print("doing a thing")
    }
}

func acceptSending(_ arg: sending @isolated(any) () async -> Void) {
}

Expected behavior

This function is not nonisolated and should not qualify for migration.

Environment

Apple Swift version 6.3-dev (LLVM 35f48306184cd25, Swift a69dbb3)
Target: arm64-apple-macosx26.0
Build config: +assertions

Additional information

No response

[xedin]

cc @AnthonyLatsis