Revise handling of boolean vectors #3593
Description
To create executable code with LLVM, both the C++ and Python bridge currently create code that instantiates cc::stdvec<i1> values with data arrays of type cc.array<i8 x ?>. We hence have currently a bunch of different places that do conversions from i1 to i8 and back to deal with items in vectors.
We should update all bridge code to instead always keep booleans as i1s, regardless of where they are used, and add a pass to do the necessary data conversion during compilation depending on the backend. Along with those bridge updates, we probably need to make the corresponding changes in the argument handling (marshalling).