mlkem768 avx2 - updated gen matrix + SCT

[tfaoliveira-sb]

performance @ 11700K master (193KB):

keypair       , 83988
enc           , 80962
dec           , 81968

this branch (with spectre v1 protections) (140KB):

keypair       , 42272
enc           , 39200
dec           , 40222

pq-crystals avx2 (adding the sizes of the different *.so files yields 176KB -- needs to be double checked in any case):

keypair, 37274
enc    , 34704
dec    , 38814

[tfaoliveira-sb]

closed as this branch is superseded by work being done on https://github.com/formosa-crypto/formosa-mlkem/tree/mlkem768_avx2_gen_matrix_sct_newparse / https://github.com/formosa-crypto/formosa-mlkem/tree/mlkem768_avx2_gen_matrix_sct_newparse_master