Par functions for Bitraverse

[catostrophe]

Added parBitraverse, parBisequence, parLeftTraverse, parLeftSequence

[codecov-io]

Codecov Report

Merging #2750 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #2750      +/-   ##
==========================================
+ Coverage   95.34%   95.35%   +0.01%     
==========================================
  Files         363      363              
  Lines        6782     6798      +16     
  Branches      290      286       -4     
==========================================
+ Hits         6466     6482      +16     
  Misses        316      316

Impacted Files	Coverage Δ
testkit/src/main/scala/cats/tests/CatsSuite.scala	33.33% <ø> (ø)	⬆️
core/src/main/scala/cats/syntax/parallel.scala	80% <100%> (+9.41%)	⬆️
core/src/main/scala/cats/Parallel.scala	90% <100%> (+1.53%)	⬆️

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[LukaJCB]

Looks good to me, thanks @catostrophe! :)

[kailuowang]

Thanks a lot for your contribution!
An easy way to clean the commit history up might be hard reset this branch to remote master and then cherry pick your actual change commit 0922a78 then merge the conflicts.
something like
if you don't have an upstream remote yet

git remote add upstream git@github.com:typelevel/cats.git

Then from you branch

git reset --hard upstream/master
git cherry-pick 0922a78

if git reports some conflicts, you can resolve those and run

git add . 
git cherry-pick --continue

then finally

git push -f

Also is it possible that we add more tests? I can see that these tests are similar to the ones ParNonEmptyTraverse has but I am not sure if that's sufficient either. Tests like ParSequence would be nice IMO.

[catostrophe]

@kailuowang fixed but the doc build is failing :(

[LukaJCB]

I restarted the build and cleared the cache, should work now :)

[LukaJCB]

Thanks as always @catostrophe