avoid "0 bytes of initcode" at top level

For the constructor of the test contract, we actually set pgm directly in the EVM state and so the initcode is not visible in the CallContext/Message

Author: 0xkarmacoma

src/halmos/traces.py

@@ -186,7 +186,7 @@ def render_trace(context: CallContext, file=sys.stdout) -> None:
             # TODO: print in debug mode
             ...
 
-        initcode_str = f"<{byte_length(message.data)} bytes of initcode>"
+        initcode_str = f"<{byte_length(message.data)} bytes of initcode>" if context.depth > 1 else "constructor()"
         print(
             f"{indent}{call_scheme_str}{addr_str}::{initcode_str}{value_str}", file=file
         )