Include source location in JSON/XML property output

[tautschnig]

Unlike the plain-text variant, neither JSON nor XML included source
locations for each of the properties being reported upon by a
goto-checker.

Fixes: #6651

• 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.

[TGWDB]

This is a placeholder to ensure this does not get merged immediately due to changes to XML output. Apologies for adding it, I should be able to remove it in a few days.

[codecov]

Codecov Report

Merging #6696 (55b5aa6) into develop (05e1fd6) will increase coverage by 0.02%.
The diff coverage is 96.80%.

❗ Current head 55b5aa6 differs from pull request most recent head 88c5acc. Consider uploading reports for the commit 88c5acc to get more accurate results

@@             Coverage Diff             @@
##           develop    #6696      +/-   ##
===========================================
+ Coverage    76.89%   76.91%   +0.02%     
===========================================
  Files         1582     1583       +1     
  Lines       183170   183352     +182     
===========================================
+ Hits        140840   141026     +186     
+ Misses       42330    42326       -4     

Impacted Files	Coverage Δ
src/goto-instrument/reachability_slicer_class.h	100.00% <ø> (ø)
jbmc/src/jbmc/jbmc_parse_options.cpp	72.46% <50.00%> (ø)
...c/solvers/smt2_incremental/convert_expr_to_smt.cpp	65.35% <92.45%> (+4.02%)	⬆️
src/cbmc/cbmc_parse_options.cpp	77.61% <100.00%> (+0.04%)	⬆️
src/goto-checker/properties.cpp	80.53% <100.00%> (+0.35%)	⬆️
.../goto-instrument/goto_instrument_parse_options.cpp	69.36% <100.00%> (+0.11%)	⬆️
src/goto-instrument/reachability_slicer.cpp	99.34% <100.00%> (+0.07%)	⬆️
src/goto-programs/remove_calls_no_body.cpp	100.00% <100.00%> (ø)
...t/solvers/smt2_incremental/convert_expr_to_smt.cpp	100.00% <100.00%> (ø)
src/goto-programs/xml_expr.cpp	51.21% <0.00%> (-3.05%)	⬇️
... and 18 more

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