[Bug]: no warning on unused client initializer param(s)

### Describe the bug

If `clientInitialization.parameters` contains values that aren't used in any routes (client or its sub-clients), a diagnostic warning should be produced (maybe even an error as this seems like an authoring mistake).

### Reproduction

tcgc version 0.54.0

### Checklist

- [x] Follow our [Code of Conduct](https://github.com/azure/typespec-azure/blob/main/CODE_OF_CONDUCT.md)
- [x] Check that this issue is about the Azure libraries for typespec. For bug in the typespec language or core libraries file it in the [TypeSpec repo](https://github.com/Microsoft/TypeSpec/issues/new/choose)
- [x] Check that there isn't already an issue that request the same bug to avoid creating a duplicate.
- [x] The provided reproduction is a [minimal reproducible example](https://stackoverflow.com/help/minimal-reproducible-example) of the bug.