[NFC] Use sclf implementation of + - * / operators, move them and `negate` to SignedNumeric extension
[NFC] Use sclf implementation of + - * / operators, move them and `negate` to SignedNumeric extension

apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation