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ARROW-7705: [Rust] Initial sort implementation

This implements `sort_to_indices` which returns an u32 array of indices that results in the array being sorted. It then implements `sort` by using `take` to sort the array.

Similar to the approach taken in CPP, I think we can start with a correct approach, then focus on performance after. I will keep this PR a draft for comments and until I complete the initial sort implementation (including sorting in descending order).

Closes #6306 from nevi-me/ARROW-7705

Authored-by: Neville Dipale <nevilledips@gmail.com>
Signed-off-by: Neville Dipale <nevilledips@gmail.com>