Validate injectivity of use/defs

[toinehartman]

This PR modifies the tests in two related ways.

1. Check that use/defs are injective, i.e. any use only maps to definitions of overloaded names.
2. Add a test use/defs of fields of syntax constructors.

Closes #2632

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 46%. Comparing base (0d4f663) to head (9c1f55d).
⚠️ Report is 20 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##              main   #2631   +/-   ##
=======================================
  Coverage       46%     46%           
- Complexity    6672    6682   +10     
=======================================
  Files          795     795           
  Lines        65878   65893   +15     
  Branches      9870    9878    +8     
=======================================
+ Hits         30679   30701   +22     
+ Misses       32824   32819    -5     
+ Partials      2375    2373    -2     

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud