Issue 3059: Move Parallel instances into instance packages for the type constructors they characterize

[barambani]

Addresses #3059 .

[codecov-io]

Codecov Report

Merging #3099 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3099      +/-   ##
==========================================
- Coverage   93.49%   93.49%   -0.01%     
==========================================
  Files         368      368              
  Lines        6983     6998      +15     
  Branches      195      198       +3     
==========================================
+ Hits         6529     6543      +14     
- Misses        454      455       +1

Impacted Files	Coverage Δ
core/src/main/scala/cats/instances/vector.scala	100% <100%> (ø)	⬆️
core/src/main/scala/cats/instances/list.scala	100% <100%> (ø)	⬆️
core/src/main/scala/cats/instances/either.scala	100% <100%> (ø)	⬆️
testkit/src/main/scala/cats/tests/Helpers.scala	96% <0%> (-4%)	⬇️
...cala/cats/kernel/instances/FunctionInstances.scala	96.96% <0%> (-3.04%)	⬇️
core/src/main/scala/cats/data/WriterT.scala	91.26% <0%> (ø)	⬆️
core/src/main/scala/cats/data/Ior.scala	98.52% <0%> (ø)	⬆️
core/src/main/scala/cats/syntax/semigroup.scala	75% <0%> (+25%)	⬆️

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[kailuowang]

thanks very much! looks good to me except one nitpick, I think all the deprecation version should be 2.1.0

[barambani]

good point, I'll change them. Thanks.