Reorganize the repo structure (#2503)

Co-authored-by: Francisco Giordano <frangio.1@gmail.com>

scripts/prepack.sh

@@ -1,10 +1,12 @@
 #!/usr/bin/env bash
 
 set -euo pipefail
+shopt -s globstar
 
 # cross platform `mkdir -p`
 node -e 'fs.mkdirSync("build/contracts", { recursive: true })'
 
-cp artifacts/*.json build/contracts
+cp artifacts/contracts/**/*.json build/contracts
+rm build/contracts/*.dbg.json
 
 node scripts/remove-ignored-artifacts.js