De-duplicate and fix code of value-set backed function pointer removal

[tautschnig]

The existing code suffered from the same problems that were previously
fixed in e4d7411 for type-based function pointer removal. Really,
there should just be one such implementation across the code base.

• 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).
• 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.

[martin-cs]

Yes! I still have plans on making function pointer removal A. more modular w.r.t. where the candidate sets come from and B. more optional. This is definitely a step in the right direction.

[codecov]

Codecov Report

Merging #6985 (8eef445) into develop (83850e1) will increase coverage by 0.00%.
The diff coverage is 70.68%.

@@           Coverage Diff            @@
##           develop    #6985   +/-   ##
========================================
  Coverage    77.83%   77.84%           
========================================
  Files         1571     1570    -1     
  Lines       180484   180439   -45     
========================================
- Hits        140488   140468   -20     
+ Misses       39996    39971   -25     

Impacted Files	Coverage Δ
...variable-sensitivity/variable_sensitivity_domain.h	100.00% <ø> (ø)
src/ansi-c/ansi_c_typecheck.cpp	67.85% <0.00%> (-8.15%)	⬇️
src/cpp/cpp_typecheck.cpp	77.70% <0.00%> (-1.52%)	⬇️
src/crangler/mini_c_parser.cpp	71.02% <0.00%> (-1.66%)	⬇️
src/goto-analyzer/goto_analyzer_parse_options.cpp	72.27% <ø> (ø)
.../goto-instrument/goto_instrument_parse_options.cpp	70.90% <ø> (ø)
src/goto-programs/string_instrumentation.cpp	25.11% <0.00%> (ø)
src/statement-list/statement_list_typecheck.h	100.00% <ø> (ø)
src/symtab2gb/symtab2gb_parse_options.cpp	60.00% <0.00%> (-3.39%)	⬇️
src/util/exception_utils.cpp	94.11% <66.66%> (-3.80%)	⬇️
... and 25 more

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