Add RenameInjectProdAndCoproduct, RenameTupleApplySyntax and RemoveSplit Scalafix rewrites

[gabro]

This PR adds these rewrites:

• RenameInjectProdAndCoproduct
• RenameTupleApplySyntax
• RemoveSplit

Two of them are super easy thanks to a feature recently landed in Scalafix (replaceSymbol). For this reason I also upgraded Scalafix to the latest milestone release for 0.5.0.

[codecov-io]

Codecov Report

Merging #1813 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1813      +/-   ##
==========================================
+ Coverage   94.88%   94.88%   +<.01%     
==========================================
  Files         241      241              
  Lines        4147     4148       +1     
  Branches       97      103       +6     
==========================================
+ Hits         3935     3936       +1     
  Misses        212      212

Impacted Files	Coverage Δ
core/src/main/scala/cats/Show.scala	100% <0%> (ø)	⬆️
core/src/main/scala/cats/data/EitherT.scala	98.27% <0%> (ø)	⬆️

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[peterneyens]

LGTM 👍

Just left one comment about the Split syntax. Not sure if want to support that one as well?

[peterneyens]

The split syntax isn't actually used below, and if it was used it, this import would clash with cats.implicits._.

If you want to test the split syntax you would have

import cats.syntax.split._ // afterwards => import cats.syntax.arrow._
import cats.instances.function._

val f = toLong split toDouble

[gabro]

ah, good catch, thanks. That's a half-baked attempt that I accidentally left in there.
I just pushed a proper version of that fix.

By the way, it'd be nice if scalafix tests were run by the CI (so that these kind of mistake would be caught). Do you think it's possible to add them to the build?

[kailuowang]

I think we should add them to the build. We can tackle it in another PR.