Function prepare_input_raw 

pub fn prepare_input_raw<T>(
    view: &RawStridedRef<'_, T>,
    n_group1: usize,
    n_group2: usize,
    conj: bool,
    requires_unit_stride: bool,
    use_pool: bool,
    materialize_conj_fn: Option<fn(T) -> T>,
) -> Result<ContiguousOperand<T>, EinsumError>
where
    T: ScalarBase + 'static,

Prepare a borrowed raw input layout for GEMM.

This is the raw-layout counterpart to prepare_input_view. Direct fusable layouts do not construct StridedView wrappers; a view is created only when a copy/materialization path needs to call a generic strided kernel.