Project housekeeping

[zguesmi]

1. • Remove build/ folder and replace by artifacts/contracts/*.json. ( ⚠️ Still used by middleware team).
2. • Remove ABILegacy. (⚠️ still used by middleware team)
3. • Merge config/config*.json files.
4. • Remove scripts in ens/, scoreImporting/.
5. • Move tools/ folder to scripts/.
6. • Remove checkCopyright.sh.
7. • Remove test.sh + autotest command from package.json and README.md.
8. • Add Halborn audit to audit/.
9. • Update README
10. • Check for remaining TODOs
11. • Clean Github branches
12. • Push ABIs automatically from CI
13. • Nice to have: Use a plugin to update Copyright header