Patch object should be non-optional parameter to the selector

[bmourad01]

The patch object is required for updating congruence information during code generation, since new temporaries may be created after the linear SSA pass. Currently, the only use case is generating the conditional moves to hold the result of a comparison:

VIBES/bap-vibes/src/arm_selector.ml

Line 631 in f0c37a7

| None -> KB.return ()

If the patch remains optional, then it should error here. A better solution may be to just require a patch, which would require updating the relevant unit tests.