Add solidity contract to update the orbit chain config to enable espr…

…esso mode at the end of migration.

src/espresso-migration/UpdateChainConfig.sol

@@ -0,0 +1,13 @@
+// Example action contract to upgrade chain config to turn on espresso mode
+
+import "../precompiles/ArbOwner.sol";
+
+contract SetEspressoChainConfig {
+    function perform(string serialiazedEspressoConfig) external {
+        //The ArbOwner precomiple always lives at this addr.
+        ArbOwner arbOwner = ArbOwner(0x0000000000000000000000000000000000000070)
+        //This call must come from an account designated as an Owner by the ArbOwner contract.
+        //In practice the Owner should be the UpgradeExecutor via the execute method. 
+        arbOwner.setChainConfig(serialiazedEspressoConfig)
+    }
+}