Update Service Indicator to handle custom crypto through *_METHOD structs

[smittals2]

Issues:

CryptoAlg-2633

Description of changes:

The service indicator "update" functions were modified to check for the existence of custom crypto in RSA_METHOD and EC_KEY_METHOD structs. If custom crypto is utilized for a given operation, the service indicator should not be updated. The checks are conservative and do not update the service indicator for a signing operation for EC/RSA keys if either custom sign or sign_sig/sign_raw functionality is provided - regardless of whether these may be invoked.

Testing:

Tested both EC_KEY_METHOD and RSA_METHOD with custom crypto and ensured the service indicator was not updating.

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

All modified and coverable lines are covered by tests ✅

Project coverage is 78.47%. Comparing base (7090b90) to head (c474dd4).
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1857      +/-   ##
==========================================
+ Coverage   78.46%   78.47%   +0.01%     
==========================================
  Files         585      585              
  Lines       99457    99511      +54     
  Branches    14236    14248      +12     
==========================================
+ Hits        78038    78094      +56     
+ Misses      20784    20781       -3     
- Partials      635      636       +1     

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[nebeid]

Why the custom EC sign is well defined and checked for the data it generates while this is not the case for RSA test? Is it more tedious for RSA?

[smittals2]

Yes it is more complex to emulate the signing behavior for RSA keys. Even more so because we'd have to define both the sign and sign_raw functionalities (since RSA_PSS keys directly call sign_raw). It shouldn't matter either way, all we care about is the existence of custom function pointers (sort of hand waving what actually happens in those custom pointers however).