Function apply_rotary 

pub fn apply_rotary(
    x: &mut [f32],
    row_len: usize,
    rope_dim: usize,
    pos: &[usize],
    fc: &[(f32, f32)],
    inverse: bool,
)

apply_rotary_emb on the last rope_dim elements of each row_len-wide row of x, row r at position pos[r]; adjacent pairs are complex numbers, multiplied in f32, written back bf16.