Vendor defined mechanism in MechanismWithParam

[ChikenL00p]

Hello,

This pull request introduces minimal changes required for supporting GOSTR mechanisms within the library.
There is a document describing all GOSTR mechanisms. There is a lot of overlap in the NIST implementation, but to ensure compatibility, the constants are chosen from the vendor-defined range (0x80000000 | 0x54321xxx).
I did not add new constants for the GOSTR parameter, but added a check in the MechanismWithParam class for the vendor-defined mechanism and to interpret the mechanism parameters as a set of bytes if the mechanism parameters are used.

The implementation has been successfully tested against two different vendor PKCS#11 libraries supporting GOST algorithms, specifically verifying data signing functionality.
These changes are backward-compatible and do not affect the existing operation of non-vendor-defined mechanisms.

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.92%. Comparing base (1ff2114) to head (0239fcd).
⚠️ Report is 5 commits behind head on master.

Files with missing lines	Patch %	Lines
pkcs11/_pkcs11.pyx	33.33%	4 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##           master     #217      +/-   ##
==========================================
- Coverage   90.17%   89.92%   -0.25%     
==========================================
  Files          15       15              
  Lines        2625     2630       +5     
  Branches       29       29              
==========================================
- Hits         2367     2365       -2     
- Misses        255      262       +7     
  Partials        3        3              

Flag	Coverage Δ
unittests	89.92% <33.33%> (-0.25%)	⬇️

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