Add add_scalar kernel

[viirya]

Which issue does this PR close?

Closes #1153.

Rationale for this change

What changes are included in this PR?

Are there any user-facing changes?

[jhorstmann]

I think you could reuse simd_float_unary_math_op here with a small modification, that method should work for any primitive types without the restriction on T: datatypes::ArrowFloatNumericType

[viirya]

Sounds good. Didn't find simd_float_unary_math_op there. Seems okay. Let me update.

[codecov-commenter]

Codecov Report

Merging #1151 (9aec376) into master (719096b) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff            @@
##           master    #1151    +/-   ##
========================================
  Coverage   82.55%   82.56%            
========================================
  Files         169      170     +1     
  Lines       50456    50623   +167     
========================================
+ Hits        41655    41797   +142     
- Misses       8801     8826    +25     

Impacted Files	Coverage Δ
arrow/src/compute/kernels/arithmetic.rs	84.64% <100.00%> (+0.50%)	⬆️
parquet/src/arrow/array_reader.rs	77.23% <0.00%> (-1.03%)	⬇️
arrow/src/datatypes/datatype.rs	66.38% <0.00%> (-0.43%)	⬇️
parquet_derive/src/parquet_field.rs	66.21% <0.00%> (-0.23%)	⬇️
arrow/src/array/transform/mod.rs	85.56% <0.00%> (-0.14%)	⬇️
arrow/src/array/builder.rs	86.49% <0.00%> (-0.01%)	⬇️
parquet/src/data_type.rs	76.84% <0.00%> (ø)
parquet/src/compression.rs	88.59% <0.00%> (ø)
parquet/src/arrow/arrow_writer.rs	98.07% <0.00%> (ø)
arrow/src/array/transform/utils.rs	100.00% <0.00%> (ø)
... and 8 more

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[alamb]

Looks good to me -- thank you @viirya ❤️

[viirya]

Thank you @alamb !