Add swizzle kernels for lsx and lasx

[domibel]

Both backends inherited the common swizzle, which stores the vector to a buffer and rebuilds it element by element.

LSX

qemu-loongarch64-static -cpu 'la464,lsx=on,lasx=off' -L /usr/loongarch64-linux-gnu ./test/test_xsimd
[doctest] doctest version is "2.4.9"
[doctest] run with "--help" for options
===============================================================================
[doctest] test cases:  410 |  410 passed | 0 failed | 0 skipped
[doctest] assertions: 5985 | 5985 passed | 0 failed |
[doctest] Status: SUCCESS!

LASX

qemu-loongarch64-static -cpu 'la464,lsx=on,lasx=on' -L /usr/loongarch64-linux-gnu ./test/test_xsimd
[doctest] doctest version is "2.4.9"
[doctest] run with "--help" for options
===============================================================================
[doctest] test cases:  410 |  410 passed | 0 failed | 0 skipped
[doctest] assertions: 7921 | 7921 passed | 0 failed |
[doctest] Status: SUCCESS!

Also tested natively on Loongson-3A6000.

[serge-sans-paille]

Thanks!