Add cats.kernel.instances.finiteDuration package

[travisbrown]

I know #3036 isn't a high priority but this is a trivial fix, and I'd personally like to see it in 2.0.0. The name matches cats.instances.finiteDuration.

No tests, but there are no tests for the duration version, either. I confirmed that the following works:

scala> import cats.kernel.instances.finiteDuration._
import cats.kernel.instances.finiteDuration._

scala> import scala.concurrent.duration.FiniteDuration
import scala.concurrent.duration.FiniteDuration

scala> cats.kernel.LowerBounded[FiniteDuration]
res0: cats.kernel.LowerBounded[scala.concurrent.duration.FiniteDuration] = cats.kernel.instances.FiniteDurationOrder@5ac7386c

scala> cats.kernel.Hash[FiniteDuration]
res1: cats.kernel.Hash[scala.concurrent.duration.FiniteDuration] = cats.kernel.instances.FiniteDurationOrder@5ac7386c

Shouldn't break source compatibility and definitely doesn't break bincompat.

[codecov-io]

Codecov Report

Merging #3037 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3037   +/-   ##
=======================================
  Coverage   93.46%   93.46%           
=======================================
  Files         368      368           
  Lines        6975     6975           
  Branches      187      187           
=======================================
  Hits         6519     6519           
  Misses        456      456

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[LukaJCB]

I don't see how this breaks source compatibility, so I think this could go in whenever, no?

[travisbrown]

Yeah, think so.

[LukaJCB]

Oh okay, now that I reparse your sentence, I think you probably just had a typo 👍

[travisbrown]

@LukaJCB Yeah, sorry, corrected.