Custom body to be sent to URL from Credentials

[diachenko-mischa]

Here credentials file specifies the endpoint that
should be used to retrieve authentication token.
HNAV backend, which implements mTLS authentication also conforms to a bit different body and response schema.

Add a possibility to add a custom body for the authentication request and parsing of token from HNAV mTLS server.

Relates-To: HERESDK-7942

[codecov]

Codecov Report

Attention: Patch coverage is 92.95775% with 5 lines in your changes missing coverage. Please review.

Project coverage is 80.29%. Comparing base (66cb092) to head (42e4464).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...lp-cpp-sdk-authentication/src/SignInResultImpl.cpp	90.62%	0 Missing and 3 partials ⚠️
...dk-authentication/src/AuthenticationClientImpl.cpp	96.67%	1 Missing ⚠️
olp-cpp-sdk-core/src/utils/Url.cpp	88.89%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1620      +/-   ##
==========================================
+ Coverage   80.23%   80.29%   +0.06%     
==========================================
  Files         348      348              
  Lines       13882    13933      +51     
  Branches     1483     1490       +7     
==========================================
+ Hits        11138    11187      +49     
- Misses       2146     2147       +1     
- Partials      598      599       +1     

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[rustam-gamidov-here]

No comments to the code but it make sense to update years in the files changed