precompiles: Add BLS precompiles IDs

[rodiazet]

Preparation to implementation of EIP-2537: "Precompile for BLS12-381 curve operations".

[codecov]

Codecov Report

Attention: Patch coverage is 23.80952% with 48 lines in your changes missing coverage. Please review.

Project coverage is 94.01%. Comparing base (6974fd7) to head (4ded90a).

Files with missing lines	Patch %	Lines
test/state/precompiles.cpp	4.00%	48 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #984      +/-   ##
==========================================
- Coverage   94.29%   94.01%   -0.28%     
==========================================
  Files         143      143              
  Lines       16142    16200      +58     
==========================================
+ Hits        15221    15231      +10     
- Misses        921      969      +48     

Flag	Coverage Δ
eof_execution_spec_tests	16.61% <0.00%> (-0.06%)	⬇️
ethereum_tests	26.50% <3.17%> (-0.09%)	⬇️
ethereum_tests_silkpre	18.61% <3.22%> (-0.07%)	⬇️
execution_spec_tests	17.67% <3.17%> (-0.06%)	⬇️
unittests	89.47% <23.80%> (-0.27%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
test/unittests/state_precompiles_test.cpp	100.00% <100.00%> (ø)
test/state/precompiles.cpp	78.18% <4.00%> (-21.82%)	⬇️

[chfast]

Commit pedantics: use "BLS" name and link the EIP.