[c++, r, python] read_next clean-up

[nguyenv]

Issue and/or context: #3472

This is a follow-up PR to #3293 which focuses on various clean-up.

Changes:

• Replace the contents of SOMAArray::read_next to be a thin wrapper around ManagedQuery::read_next
• Replace the contents of tiledbsoma-r sr_complete to be a thin wrapper around SOMAArray::results_complete
• Remove dead code setup_read, submit_read, and results from clib.ManagedQuery

Notes for Reviewer:

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.55%. Comparing base (bda7d97) to head (f5fe343).
Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #3450       +/-   ##
===========================================
- Coverage   86.27%   66.55%   -19.73%     
===========================================
  Files          55      139       +84     
  Lines        6339    18004    +11665     
  Branches        0     1086     +1086     
===========================================
+ Hits         5469    11982     +6513     
- Misses        870     5636     +4766     
- Partials        0      386      +386     

Flag	Coverage Δ
libtiledbsoma	55.80% <100.00%> (?)
python	86.32% <ø> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
python_api	86.32% <ø> (+0.04%)	⬆️
libtiledbsoma	49.81% <100.00%> (∅)

[johnkerl]

LGTM! Although I defer to @bkmartinjr who made the request.