++sew jet

[dozreg-toplud]

Jet for ++sew gate. Makes non-jetted urwasm tests 15 times faster.

Note: I set bail:fail on non-atomic a for the same reason it fails in ++can jet: in Hoon this argument gets passed to ++lsh and ++rsh which take +$bite, which can be a cell. I fail the jet on other non-atomic arguments just in case.

I also don't want to bother with the case of indirect b and/or c so I punt on them being indirect.