Make more Reducible Collections Counted

[alexanderkiel]

Before some reducible collections like from the iterators namespace and such created by the with-open-coll macro did not implement Counted. So they could not directly counted and instead had to be converted into a vector first.

Needed by #1382

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.94%. Comparing base (7a8d388) to head (a80b1c1).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2052      +/-   ##
==========================================
- Coverage   95.00%   94.94%   -0.07%     
==========================================
  Files         325      325              
  Lines       19974    19976       +2     
  Branches      468      483      +15     
==========================================
- Hits        18977    18966      -11     
+ Misses        529      527       -2     
- Partials      468      483      +15     

see 4 files with indirect coverage changes