Specialize [byte] as arrow Binary / FixedSizeBinary

[jleibs]

We currently treat [byte] as Lists / FixedSizedLists of u8, which adds an extra layer of indirection. Sometimes this is nice for API symmetry, such as in the Tensor u8 buffers, but it would be nice to have an attribute that forces it to use Binary instead.

[emilk]

We now support this in codegen with attr.rerun.override_type: binary

Actually using it is part of #11068