refactor precompiles

[0x0ece]

Refactored precompiles.

Done.

1. Refactor precompiles to sort-of unify their logic (pending differences imposed by Agave)
2. Improved support for precompiles in fd_exec_instr_test.c
3. Test are in solana-conformance / test-vectors. We pass all tests assuming: 1) agave has verify_strict, 2) soft check for result 0 vs err, errors match in most cases but not all. Error vs success always match.

In future PRs.

1. Properly invoke precompiles, these shouldn't be native programs, but run right after ed25519 sigverify.
2. Ed25519 implements verify_strict, but in Agave they have verify. We should either implement non-strict verify or change it in Agave.