Function find_impl 

pub async fn find_impl(
    name: &str,
    lsp_client: &mut LspClient,
    file_tracker: &mut FileTracker,
    project_root: &Path,
) -> Result<Vec<SymbolMatch>>

Find concrete implementations of an interface method using textDocument/implementation.

Resolves the symbol’s location via workspace/symbol, then queries the LSP for all concrete implementations (classes that implement the interface).

Errors

Returns an error if the symbol is not found or the LSP request fails.