goto-programs: Replace uses of namespacet::follow

[tautschnig]

This is deprecated. Use suitable variants of follow_tag instead.

• 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.

[codecov]

Codecov Report

Attention: Patch coverage is 73.07692% with 21 lines in your changes are missing coverage. Please review.

Project coverage is 79.64%. Comparing base (d7b229e) to head (60dc466).
Report is 2 commits behind head on develop.

Files	Patch %	Lines
src/goto-programs/interpreter.cpp	42.85%	12 Missing ⚠️
src/goto-programs/graphml_witness.cpp	0.00%	5 Missing ⚠️
src/goto-programs/destructor.cpp	80.00%	1 Missing ⚠️
src/goto-programs/interpreter_evaluate.cpp	0.00%	1 Missing ⚠️
src/goto-programs/json_expr.cpp	91.66%	1 Missing ⚠️
src/goto-programs/xml_expr.cpp	90.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8230   +/-   ##
========================================
  Coverage    79.64%   79.64%           
========================================
  Files         1684     1683    -1     
  Lines       195670   195670           
========================================
+ Hits        155841   155843    +2     
+ Misses       39829    39827    -2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.