Make setTwist/twist take/return a const reference. #5498

Job	Run time
macos (macOS-GCC11-NoMPI-Real)	36m 54s
spack-centos-stream (GCC11-NoMPI-Debug-Real)	27m 31s
spack-centos-stream (GCC11-NoMPI-NoOMP-Real)	31m 46s
spack-centos-stream (GCC11-NoMPI-NoOMP-Complex)	26m 19s
spack-centos-stream (GCC11-NoMPI-Sandbox-Real)	6m 15s
linux (GCC9-NoMPI-Debug-Real)	25m 26s
linux (GCC9-NoMPI-NoOMP-Real)	26m 19s
linux (GCC9-NoMPI-NoOMP-Complex)	27m 35s
linux (GCC9-NoMPI-Sandbox-Real)	5m 2s
linux (GCC9-MPI-Gcov-Real)	40m 35s
linux (GCC9-MPI-Gcov-Complex)	56m 13s
linux (GCC11-NoMPI-Werror-Real)	32m 55s
linux (GCC11-NoMPI-Werror-Complex)	25m 55s
linux (GCC11-NoMPI-Werror-Real-Mixed)	30m 0s
linux (GCC11-NoMPI-Werror-Complex-Mixed)	28m 55s
linux (Clang14-NoMPI-ASan-Real)	27m 38s
linux (Clang14-NoMPI-ASan-Complex)	37m 57s
linux (Clang14-NoMPI-UBSan-Real)	32m 10s
linux (Clang16-NoMPI-Offload-Real)	41m 38s
	9h 27m 3s

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