[Foundation] adjust inline of append and initialization functions (#17027)
[Foundation] adjust inline of append and initialization functions (#17027)

* [Foundation] adjust inline of append and initialization functions and use _copyContents(initialzing:) to avoid performance regressions while using generic collection/sequence APIs

* Add the Array<UInt8> specialization back for append to Data

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