Add MonoidK and SemigroupK instances for Function1 and also a Semigroup instance for Function1

[lvicentesanchez]

This PR address #684 by adding MonoidK and SemigroupK instances for Function1; it also adds a Semigroup instance for Funcion1.

[codecov-io]

Current coverage is 83.93%

Merging #691 into master will increase coverage by +0.04% as of f68f4d0

@@            master    #691   diff @@
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  Files          162     162       
  Stmts         2217    2222     +5
  Branches        74      74       
  Methods          0       0       
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+ Hit           1860    1865     +5
  Partial          0       0       
  Missed         357     357       

Review entire Coverage Diff as of f68f4d0

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[ceedubs]

Could you make this private[std] sealed trait Function1Instances0 please? This will make it consistent with the work done in #612.

[ceedubs]

I left a couple very minor comments, but other than that, this looks great! Thank you.

[lvicentesanchez]

Ok, that should do it :)

[ceedubs]

👍 looks great!

[non]

Thanks! 👍