tool-openssl: pkcs8 error output on decrypt

[justsmth]

Description of changes:

Align error output of "openssl pkcs8" when handling encrypted keys.

Testing:

Added new test to prevent regression

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license and the ISC license.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.31373% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 78.23%. Comparing base (7c02cb3) to head (c0ac3b7).

Files with missing lines	Patch %	Lines
tool-openssl/pkcs8.cc	77.14%	8 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2883   +/-   ##
=======================================
  Coverage   78.23%   78.23%           
=======================================
  Files         683      683           
  Lines      117412   117462   +50     
  Branches    16500    16509    +9     
=======================================
+ Hits        91856    91899   +43     
- Misses      24668    24676    +8     
+ Partials      888      887    -1     

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