Let NumberSmallGroups take the selection criteria of AllSmallGroups

[fingolfin]

NumberSmallGroups(96, IsAbelian) is 7, and a list of orders is accepted as
well:

gap> NumberSmallGroups( [ 1 .. 100 ] );
1048
gap> NumberSmallGroups( 96, IsAbelian );
7

A thin wrapper for now: with criteria it counts what IdsOfAllSmallGroups
returns, so it costs what that costs -- the indexed criteria narrow the range
first and only the groups a remaining criterion must be tested on get built.
Orders alone are answered from the numbers of groups, constructing nothing.

Being a wrapper, it needs nothing from the layers, so sglppow and SOTGrps gain
the feature untouched. Per-layer counting methods can follow, and so can a
place for this in whatever #67 turns the layering into.

Fixes #68

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.88%. Comparing base (ce4a0e6) to head (7bb9cd5).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #72   +/-   ##
=======================================
  Coverage   99.88%   99.88%           
=======================================
  Files         507      507           
  Lines      370982   371002   +20     
=======================================
+ Hits       370557   370577   +20     
  Misses        425      425           

Files with missing lines	Coverage Δ
gap/small.gd	100.00% <ø> (ø)
gap/small.gi	97.65% <100.00%> (+0.08%)	⬆️

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