Log to file the SMT formula run by the solver

[esteffin]

This PR introduces the new --dump-smt-formula argument that logs to a file the SMT formula given to the incremental SMT solver.
This is different from the old --outfile argument as it does not run the solver, and, because of that, stops the generated file to the first (check-sat) call.

This PR requires the work to support --outfile that will be added by PR 7126, so it is dependant to its merge.

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• 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).
• My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
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[codecov]

Codecov Report

Base: 78.36% // Head: 78.38% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (481c43e) compared to base (f025c91).
Patch coverage: 79.92% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7161      +/-   ##
===========================================
+ Coverage    78.36%   78.38%   +0.02%     
===========================================
  Files         1651     1651              
  Lines       190009   190058      +49     
===========================================
+ Hits        148896   148973      +77     
+ Misses       41113    41085      -28     

Impacted Files	Coverage Δ
src/analyses/constant_propagator.h	82.35% <ø> (ø)
src/analyses/invariant_set.cpp	0.00% <0.00%> (ø)
src/analyses/invariant_set.h	0.00% <0.00%> (ø)
src/ansi-c/c_expr.h	100.00% <ø> (ø)
src/ansi-c/c_typecheck_base.h	100.00% <ø> (ø)
src/ansi-c/scanner.l	63.39% <ø> (ø)
src/ansi-c/ansi_c_convert_type.cpp	79.48% <8.16%> (ø)
.../src/java_bytecode/character_refine_preprocess.cpp	54.27% <28.57%> (ø)
src/analyses/local_may_alias.cpp	63.80% <33.33%> (ø)
src/analyses/custom_bitvector_analysis.cpp	55.96% <50.00%> (ø)
... and 135 more

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[tautschnig]

Ok with the changes so far, but you'll need to update the man page to make CI pass.

[tautschnig]

Random place for comment: the commit message needs to be reviewed (spurious "---------------------", missing words after "that is being").

[thomasspriggs]

I am not particularly satisfied with the code duplication this PR introduces between the smt_piped_solver_processt class and the smt_incremental_dry_run_solvert class. However I'd prefer to get this feature merged and worry about clean-up afterwards. I have a potential refactor to resolve this, which I will raise as a follow-up myself.