Frontend assumes names from Wasm's `name` section are unique

However [according to the spec](https://webassembly.github.io/spec/core/appendix/custom.html#name-section)

> Names need not be unique.

So far names turned out to be unique in our examples and fixtures. When switching the default panic strategy from `immediate-abort` to `abort` (#1339), `Felt` related formatting code produces duplicate function names in the `name` section for multiple examples/fixtures.

### Reproduction

```sh
cargo make midenc # build bin/midenc
cd examples/counter-contract
RUSTFLAGS="-C panic=abort" ../../bin/midenc miden-project.toml

thread 'main' (185908) panicked at hir/src/ir/operation.rs:209:17:
Unable to insert builtin.function in symbol table of builtin.module: symbol _RNvXsq_NtCs9z35J0Io6i7_11miden_field10wasm_midenNtB5_16FeltFromIntErrorNtNtCs9YlYMtCqyny_4core3fmt5Debug3fmt is already registered to another operation _RNvXsq_NtCs9z35J0Io6i7_11miden_field10wasm_midenNtB5_16FeltFromIntErrorNtNtCs9YlYMtCqyny_4core3fmt5Debug3fmt.
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
```

### Why this was hidden so far

It's formatting related code which until recently wasn't supported for the Miden target and got eliminated due to `panic=immediate-abort`. With `panic=abort` it stays around.

`Felt` is special but I think regardless we must not assume that names in the `name` section are unique.

### Proposed fix

Try to derive a unique HIR symbol, e.g. by combining the name with the unique function index.

The issue is in the frontend's handling of the WebAssembly name section. Look at the symbol table insertion in `hir/src/ir/operation.rs` around line 209. The fix involves generating a unique HIR symbol, perhaps by combining the function name with its index. Start by building the compiler with `cargo make midenc`, then reproduce the error in `examples/counter-contract` with the given command. Check how function names are currently registered and where duplicates arise.

Scritto dal modello di indicizzazione a partire dal testo della issue.