V128: proper symbolic and concolic handling

[chambart]

Still TODO from previous PR #696 are I8x16 and I16x8 additions

[zapashcanon]

I think you need to add a v128_symbol in src/cmd/cmd_replay.ml to fix the tests. This is because your are now adding one such import in owi iso for which there is a test that is replayed later. (And then you'll need a promote to update some functions indices in various execution traces)

[zapashcanon]

Thanks!