Added compute::arity_assign

[jorgecarleitao]

The clone-on-write counterpart of compute::arity - it avoids memcopies when the lhs can be mutated in place. It offers a 2.2x improvement when both arrays have values and validity vs compute::arity:

apply_mul null 2^20     time:   [142.24 us 142.85 us 143.47 us]
mul null 2^20           time:   [318.90 us 319.91 us 320.93 us]

[codecov]

Codecov Report

Merging #1070 (aa4eafa) into main (76d2a39) will increase coverage by 0.01%.
The diff coverage is 92.59%.

@@            Coverage Diff             @@
##             main    #1070      +/-   ##
==========================================
+ Coverage   81.00%   81.02%   +0.01%     
==========================================
  Files         365      366       +1     
  Lines       35023    35050      +27     
==========================================
+ Hits        28372    28400      +28     
+ Misses       6651     6650       -1     

Impacted Files	Coverage Δ
src/compute/arity_assign.rs	92.59% <92.59%> (ø)
src/io/ipc/write/serialize.rs	96.15% <0.00%> (-0.15%)	⬇️
src/io/ipc/read/stream_async.rs	74.38% <0.00%> (+0.82%)	⬆️
src/bitmap/assign_ops.rs	83.87% <0.00%> (+2.41%)	⬆️

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