DM-40254: Improve handling of calibration datasets in graph builder

[andy-slac]

There may be multiple calibration datasets for the same dataset type and
data ID in one graph (with different timespans). This patch changes internal
graph builder structure for prerequisite datasets to allow multiple datasets
for one data ID.

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes

[codecov]

Codecov Report

Patch coverage: 60.46% and project coverage change: -0.09% ⚠️

Comparison is base (7e71b86) 82.67% compared to head (caa5298) 82.59%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #362      +/-   ##
==========================================
- Coverage   82.67%   82.59%   -0.09%     
==========================================
  Files          66       66              
  Lines        7321     7349      +28     
  Branches     1432     1443      +11     
==========================================
+ Hits         6053     6070      +17     
- Misses       1019     1031      +12     
+ Partials      249      248       -1     

Files Changed	Coverage Δ
python/lsst/pipe/base/graphBuilder.py	61.20% <60.46%> (-0.38%)	⬇️

... and 1 file with indirect coverage changes

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