Handle infinity in the back-end and in the simplifier

[tautschnig]

We need to support at least object_size operations over infinity in the
back-end as the postponed evaluation iterates over all objects, which
may include ones that have infinite size.

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[codecov]

Codecov Report

Attention: Patch coverage is 82.92683% with 7 lines in your changes missing coverage. Please review.

Project coverage is 77.79%. Comparing base (e42a46d) to head (08b12ec).
Report is 2920 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/util/simplify_expr_int.cpp	69.56%	7 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #6914   +/-   ##
========================================
  Coverage    77.78%   77.79%           
========================================
  Files         1568     1568           
  Lines       180269   180309   +40     
========================================
+ Hits        140230   140263   +33     
- Misses       40039    40046    +7     

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[peterschrammel]

Isn't the actual size of infinity still bounded by the maximum offset size in the current pointer encoding?

[tautschnig]

Closing in favour of #8469.