Make chain setup in scripts idempotent

Author: larskuhtz

src/Chainweb.sol

@@ -44,6 +44,10 @@ contract Chainweb is CommonBase {
     }
 
     function setupChainsForScript() public {
+        if (_chainForks.length > 0) {
+            console.log("Chain forks already set up, skipping setup.");
+            return;
+        }
         console.log("Setting main RPC node for", _chains, "chains");
         for (uint256 i = 0; i < _chains; i++) {
             if (bytes(_hostUrl).length > 0) {