SMT2: fix for encoding of range-typed symbols

[kroening]

The SMT2 backend now adds a constraint to ranged-typed symbols that prevent out-of-range values.

The SMT2 backend uses a bit-vector encoding for finite integer ranges, which uses a logarithmic number of bits in the width of the interval. If the width of the interval is not a power of two, values above the upper end of the range are possible.

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• 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).
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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.55%. Comparing base (30ca13c) to head (b9ef902).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8969   +/-   ##
========================================
  Coverage    80.55%   80.55%           
========================================
  Files         1706     1707    +1     
  Lines       188982   189012   +30     
  Branches        73       73           
========================================
+ Hits        152227   152254   +27     
- Misses       36755    36758    +3     

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