Fix two main stack frames when an entrypoint is curried in the debugger

Clarification and motivation

If I try debugging a contract with a curried entrypoint, I'll get two main stack frames. This is because the last meta in the source mapper is an environment with an uncurried entrypoint with a generated main name (like main#123). We need to find a way to distinguish them.

Acceptance criteria

• We have only one stack frame with a main entrypoint name.