[CI] Lookup for code sign tool in App Certification Kit folder.

[NlightNFotis]

When there is at least one version of the Windows SDK installed,
this folder is guaranteed to be present (the App Certification Kit
is installed along the windows SDK).

• Each commit message has a non-empty body, explaining why the change was made.
• 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.
• White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[codecov]

Codecov Report

Merging #5984 (baa2f70) into develop (a387193) will increase coverage by 0.07%.
The diff coverage is 94.79%.

@@             Coverage Diff             @@
##           develop    #5984      +/-   ##
===========================================
+ Coverage    75.04%   75.12%   +0.07%     
===========================================
  Files         1433     1435       +2     
  Lines       155817   156301     +484     
===========================================
+ Hits        116932   117414     +482     
- Misses       38885    38887       +2     

Impacted Files	Coverage Δ
...nalyses/variable-sensitivity/abstract_object_set.h	100.00% <ø> (ø)
...lyses/variable-sensitivity/abstract_value_object.h	87.71% <ø> (ø)
...ses/variable-sensitivity/constant_abstract_value.h	100.00% <ø> (ø)
...s/variable-sensitivity/value_set_abstract_object.h	100.00% <ø> (ø)
src/ansi-c/c_typecheck_base.h	100.00% <ø> (ø)
src/ansi-c/expr2c_class.h	100.00% <ø> (ø)
src/goto-programs/goto_convert_class.h	87.30% <ø> (ø)
src/goto-symex/goto_state.h	100.00% <ø> (ø)
src/solvers/smt2/smt2_conv.h	100.00% <ø> (ø)
src/util/expr.h	97.84% <ø> (ø)
... and 48 more

---

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[thomasspriggs]

The change looks good as far as I can see. Can you provide a link to a CI run, showing that the signing works in the packaging job again?

[NlightNFotis]

@thomasspriggs Yes, I can -> https://github.com/NlightNFotis/cbmc/runs/2220703073?check_suite_focus=true

Here it's failing because it can't import the certificate (because it's a GitHub secret, and I don't have access to it), rather than failing because the tool can't be found.

[thomasspriggs]

LGTM