add microkernels-prod to backend_xnnpack in build_apple_frameworks (#5795)

Summary:
Recently, previous xnnpack update includes a cmake refactor in which microkernels-prod is separated out as a static library. When we install the xnnpack_backend, we must remember to install microkernels-prod and xnnpack to make sure that it is correctly linkd with xnnpack_backend

Pull Request resolved: https://github.com/pytorch/executorch/pull/5795

Reviewed By: shoumikhin, kirklandsign

Differential Revision: D63722997

Pulled By: mcr229

fbshipit-source-id: fe98945400d11ae14086ddb185ae07e649deed1e