Resolving Keccak-256: check if arguments are identifiers early.

Previously, the check on whether the optimization was useful gas wise was done before checking if
the keccak256 opcode had identifier as arguments. Since the gas meter crashes when encountering
certain Yul opcodes (create, dataoffset, etc.), this optimizer step crashed.

test/libyul/yulOptimizerTests/loadResolver/keccak_crash.yul

@@ -0,0 +1,13 @@
+// This test used to crash: https://github.com/ethereum/solidity/issues/11801
+{
+  for {} addmod(keccak256(0x0,create(0x0, 0x0, 0x0)), 0x0, 0x0) {} {}
+}
+// ----
+// step: loadResolver
+//
+// {
+//     for { }
+//     addmod(keccak256(0x0, create(0x0, 0x0, 0x0)), 0x0, 0x0)
+//     { }
+//     { }
+// }