Add tests for Int4 kernels

* Tested kernels:
  - lhs_quant_pack_qai8dxp_f32
  - rhs_pack_nxk_qsi4cxp_qsu4cxs1s0
  - matmul_clamp_f32_qai8dxp4x8_qsi4cxp8x8_8x8x32_neon_i8mm
* Only entire matrix is tested - support for testing arbitrary
  portion of the output will come later.
* Update test framework to accommodate the new tests.
  - The new test no longer relies on DataFormat concept.
    Now the packing function for each format is explicitly called.

Signed-off-by: Viet-Hoa Do <viet-hoa.do@arm.com>

Reviewed-by: Viet-Hoa Do <viet-hoa.do@arm.com>
Approved-by: Jakub Sujak <jakub.sujak@arm.com>