[Arm64] Simplify logic for RMW hardware intrinsics (#34668)

[Arm64] Simplify logic for RMW hardware intrinsics (#34668)

* Make HW_Flag_NoRMWSemantics Intel-architecture specific and add HW_Flag_HasRMWSemantics on Arm64 in hwintrinsic.h

* Mark RMW intrinsics with the new flag in hwintrinsiclistarm64.h

* setTgtPref should be also enabled under FEATURE_HW_INTRINSICS - to allow preferential targetReg allocation on Arm64 in lsrabuild.cpp

* Redo LinearScan::BuildHWIntrinsic in lsraarm64.cpp

* Use HWIntrinsicInfo::HasRMWSemantics in GenTree::isRMWHWIntrinsic in gentree.cpp

* Remove SpecialCodeGen for ExtractAndNarrowHigh, Decrypt and Encrypt and add RMW specific codegen in hwintrinsiccodegenarm64.cpp hwintrinsiclistarm64.h