Crypto/bls12_381: optimize public key and signature aggregation

This MR optimizes public key and signature aggregation functions by using blst_p1s_add/blst_p2s_add from the blst library.

Manually testing the MR

dune runtest in src/lib_bls12_381_signature/test and src/lib_bls12_381/test

Benchmarks

dune build src/bin_test/test.exe && PROFILING="*->info" dune exec src/bin_test/test.exe && cat /tmp/test.txt on this branch.

Benchmarks on Dell XPS 13 with Intel Core Ultra 7 258V processor:

Number of public keys = 200

• Aggregate signatures

aggregate all 200 signatures (master) ........................................ 1           11.584ms 100%
aggregate signatures (in C, with check) ...................................... 1           11.420ms 101%
aggregate signatures (in C, no check) ........................................ 1            4.434ms 100%

• Aggregate public keys

aggregate all 200 pks (add_bulk) ............................................. 1            8.423ms 100%
aggregate all 200 pks (add_bulk, no check) ................................... 1            2.243ms 100%
aggregate all 200 pks (in C, with check) ..................................... 1            8.302ms 100%
aggregate all 200 pks (in C, no check) ....................................... 1            2.193ms 101%  

Number of public keys = 20_000

• Aggregate signatures

aggregate all 20000 signatures (master) ...................................... 1         1157.355ms 100%
aggregate signatures (in C, with check) ...................................... 1         1143.181ms 100%
aggregate signatures (in C, no check) ........................................ 1          443.468ms 100%  

• Aggregate public keys

aggregate all 20000 pks (add_bulk) ........................................... 1          838.745ms 100%
aggregate all 20000 pks (add_bulk, no check) ................................. 1          225.276ms 100%
aggregate all 20000 pks (in C, with check) ................................... 1          831.541ms 100%
aggregate all 20000 pks (in C, no check) ..................................... 1          219.350ms 100%

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR