Remove arrow-ord dependency in arrow-cast due to RunEndEncoded casting

[vegarsti]

#8589 introduced a dependency on arrow-ord in arrow-cast because it uses the partition kernel for casting RunEndEncoded (REE) arrays. We are trying to keep the number of dependencies to a minimum.

Probably we can also partition a (single) column using eq and an offset to look for consecutive rows which are different.

Something like

let arr = ...;
let arr_shift1 = arr.slice(1, arr.len()-1);
let transitions = eq(arr, arr_shift_1);

However, the eq kernels is also in arrow-ord so I am not sure there is a way around it

Originally posted by @alamb in #8589 (comment)

[Weijun-H]

take