Use zrot for applying Givens rotation

[kevinsung]

One of these calls to zscal can be eliminated by either merging with the one in the next loop or by redefining the Givens rotation so that it only requires one phasing operation:

ffsim/src/gates/orbital_rotation.rs

Lines 171 to 173 in 838ac25

	zscal(dim_b, phase_conj, row_i, 1);
	zdrot(dim_b, row_i, 1, row_j, 1, c, s);
	zscal(dim_b, phase, row_i, 1);

[kevinsung]

Actually, it's better to use a single call to zrot once it's available: blas-lapack-rs/blas#43