C++ front-end fixes

[tautschnig]

Please review commit-by-commit. This gets us somewhat closer to being able to process type_traits.

• Each commit message has a non-empty body, explaining why the change was made.
• Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• 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).
• 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

Attention: Patch coverage is 75.91837% with 59 lines in your changes missing coverage. Please review.

Project coverage is 77.88%. Comparing base (2523f2c) to head (83b210e).
Report is 2 commits behind head on develop.

Files	Patch %	Lines
src/cpp/parse.cpp	71.16%	47 Missing ⚠️
src/cpp/cpp_typecheck_expr.cpp	85.41%	7 Missing ⚠️
src/ansi-c/scanner.l	60.00%	2 Missing ⚠️
src/cpp/cpp_storage_spec.cpp	50.00%	1 Missing ⚠️
src/cpp/cpp_storage_spec.h	87.50%	1 Missing ⚠️
src/cpp/cpp_typecheck_resolve.cpp	80.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8275      +/-   ##
===========================================
- Coverage    78.32%   77.88%   -0.45%     
===========================================
  Files         1726     1726              
  Lines       188506   189767    +1261     
  Branches     18249    18360     +111     
===========================================
+ Hits        147646   147798     +152     
- Misses       40860    41969    +1109     

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