core: add BN254 curve support

[Turalchik]

Close #4029.

[codecov]

Codecov Report

❌ Patch coverage is 73.86364% with 23 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.08%. Comparing base (3d162dc) to head (850dde3).
⚠️ Report is 4 commits behind head on master.

Files with missing lines	Patch %	Lines
pkg/core/native/crypto.go	79.26%	10 Missing and 7 partials ⚠️
pkg/interop/native/crypto/crypto.go	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4032      +/-   ##
==========================================
- Coverage   72.48%   72.08%   -0.41%     
==========================================
  Files         364      382      +18     
  Lines       56750    57161     +411     
==========================================
+ Hits        41135    41203      +68     
- Misses      13880    14217     +337     
- Partials     1735     1741       +6     

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[roman-khimov]

Blocked till neo-project/neo#4185 resolution