KNOWNBUG test for enum-range check inside LHS of an assignment

[kroening]

This adds a test that should fail an enum-range check inside the LHS of an assignment.

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• n/a My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.55%. Comparing base (c4aaafd) to head (fbee5c1).
Report is 4 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8543   +/-   ##
========================================
  Coverage    78.55%   78.55%           
========================================
  Files         1729     1729           
  Lines       199714   199714           
  Branches     18312    18312           
========================================
  Hits        156892   156892           
  Misses       42822    42822           

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