Remove Order constraints from SortedMap and NonEmptyMap instances

[joroKr21]

SortedMap carries around its own instance of Ordering so there is no need for an implicit Order constraint unless we have to create a new SortedMap from scratch (e.g. in Monoid.empty).

Some of the removed constraints were simply not used (e.g. Show, Hash), others were used only in some methods but not others (e.g. Traverse) - note that the standard lib ++ does not require an Ordering.

These inconsistencies are accidental at best and can lead to surprising behaviour at worst (when there are incoherent Order instances in a project).

Closes #3223
Closes #2318

[codecov-io]

Codecov Report

Merging #3397 into master will increase coverage by 0.04%.
The diff coverage is 53.12%.

@@            Coverage Diff             @@
##           master    #3397      +/-   ##
==========================================
+ Coverage   92.49%   92.53%   +0.04%     
==========================================
  Files         378      379       +1     
  Lines        7956     7999      +43     
  Branches      227      224       -3     
==========================================
+ Hits         7359     7402      +43     
  Misses        597      597              

Flag	Coverage Δ
#scala_version_212	92.56% <53.12%> (?)
#scala_version_213	92.33% <53.12%> (-0.16%)	⬇️

Impacted Files	Coverage Δ
core/src/main/scala/cats/Align.scala	96.29% <ø> (ø)
core/src/main/scala/cats/FunctorFilter.scala	100.00% <ø> (ø)
core/src/main/scala/cats/Invariant.scala	92.00% <ø> (ø)
core/src/main/scala/cats/SemigroupK.scala	94.44% <0.00%> (-5.56%)	⬇️
core/src/main/scala/cats/Semigroupal.scala	95.45% <ø> (ø)
core/src/main/scala/cats/Show.scala	68.42% <ø> (+0.85%)	⬆️
core/src/main/scala/cats/UnorderedFoldable.scala	96.42% <ø> (ø)
kernel/src/main/scala/cats/kernel/Eq.scala	84.52% <ø> (ø)
kernel/src/main/scala/cats/kernel/Semigroup.scala	74.64% <0.00%> (-2.17%)	⬇️
...ala/cats/kernel/instances/SortedMapInstances.scala	82.35% <14.28%> (-17.65%)	⬇️
... and 20 more

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[joroKr21]

@travisbrown I think we should make a decision on this one before 2.2.0 because of bincompat - it modifies directly the new implicit scope instances.

[LukaJCB]

Looks good to me, just need to fix that one merge conflict. :)

[barambani]

super nitpick 😄 , now that M2 is out

Suggested change

	@deprecated("Use fromMap override without Order", "2.2.0-M2")
	@deprecated("Use fromMap override without Order", "2.2.0-M3")

or if it doesn't make it for the M3 RC1 may be. Here and the others

[travisbrown]

The conflict seems pretty simple and I think doesn't require reformatting or anything, so I'll just resolve it here through the web interface if there are no objections (and we can update the since arguments to M3 in a quick follow-up).

[codecov-commenter]

Codecov Report

Merging #3397 into master will increase coverage by 0.48%.
The diff coverage is 47.36%.

@@            Coverage Diff             @@
##           master    #3397      +/-   ##
==========================================
+ Coverage   91.99%   92.47%   +0.48%     
==========================================
  Files         383      379       -4     
  Lines        8372     8003     -369     
  Branches      212      225      +13     
==========================================
- Hits         7702     7401     -301     
+ Misses        670      602      -68     

[travisbrown]

Oh, looks like I was wrong and it does need a format. @joroKr21, sorry about that—I can grab your commits and open a new PR with them, or you could pull from here and push the format commit?

[joroKr21]

Fine by me 👍

[joroKr21]

Superseded by #3473