Add name to RandomVariable abstract base class and all concrete implementations.

[cdc-mitzimorris]

This PR implements the plan and discussion in #697

• all RandomVariable classes have a default name; names are consistent across related RVs, e.g., "diff" for differenced everywhere.

• unit tests use RV name everywhere, tests of this requirement and checks that names are set correctly are consolidated into test file test/test_interface_coverage.py

• tutorials updated as needed.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.87%. Comparing base (00352ea) to head (d6f1f4a).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #703      +/-   ##
==========================================
+ Coverage   97.85%   97.87%   +0.01%     
==========================================
  Files          51       51              
  Lines        1542     1555      +13     
==========================================
+ Hits         1509     1522      +13     
  Misses         33       33              

Flag	Coverage Δ
unittests	97.87% <100.00%> (+0.01%)	⬆️

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[github-actions]

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[cdc-mitzimorris]

@dylanhmorris @damonbayer ready for review

[dylanhmorris]

Thanks, @cdc-mitzimorris. One test needed (or flag for me if it's there and I missed it).

[cdc-mitzimorris]

@dylanhmorris - changes made - ready for re-review

[dylanhmorris]

LGTM, thanks @cdc-mitzimorris!