Closes #557, in-place implementation of expval for LightningQubit #2704

Job	Run time
C++ tests (ubuntu-22.04, lightning_qubit)	4m 44s
C++ tests (OpenBLAS) (ubuntu-22.04, lightning_qubit)	4m 52s
Python tests with OpenBLAS (ubuntu-22.04, lightning_qubit)	4m 13s
Python tests (ubuntu-22.04, lightning_qubit)	4m 14s
Build and cache Kokkos / Set Kokkos builder matrix	1s
Build and cache Kokkos / Kokkos core (SERIAL)	5s
Build and cache Kokkos / Kokkos core (OPENMP)	5s
C++ tests (multiple backends) (ubuntu-22.04, SERIAL, 4.0.01)	3m 35s
C++ tests (Kokkos) (ubuntu-22.04, lightning_kokkos, SERIAL, 4.0.01)	4m 48s
Python tests with Kokkos (ubuntu-22.04, lightning_kokkos, SERIAL, 4.0.01)	4m 22s
C++ tests (multiple backends) (ubuntu-22.04, OPENMP, 4.0.01)	3m 38s
C++ tests (Kokkos) (ubuntu-22.04, lightning_kokkos, OPENMP, 4.0.01)	4m 49s
Python tests with Kokkos (ubuntu-22.04, lightning_kokkos, OPENMP, 4.0.01)	4m 28s
Python tests with Kokkos (ubuntu-22.04, all, SERIAL, 4.0.01)	6m 6s
Python tests with Kokkos (ubuntu-22.04, all, OPENMP, 4.0.01)	6m 28s
Upload coverage data to codecov	7s
Upload coverage data to codecov	6s
	56m 41s

Provide feedback