Separate squin.qubit and squin.wire rewrites

[johnzl-777]

The current design of #148 combines the handling of rewriting from the squin.qubit and squin.wire dialects as one rewrite. @weinbe58 pointed out the double handling might not even be necessary on the basis that #25 could be implemented (then I could just handle going from squin.wire to stim) but @Roger-luo has told me if the work is already done (as it has!) then I might as well split them up (: , which I think would be good on the additional basis that there's a lot of somewhat annoying type checking going on 👍

[johnzl-777]

See the latest conversation on #148 , the decision has been made to go towards codegen instead of the standard rewrite approach