Function collect_param_idents 

pub(crate) fn collect_param_idents(
    inputs: &Punctuated<FnArg, Comma>,
    skip_first: bool,
    normalize: bool,
) -> Vec<String>

Collect parameter identifiers from a function signature.

Skips self/&self receivers unconditionally. When skip_first is true, also skips the first FnArg::Typed parameter (used for methods where the first typed argument is the self external pointer). When normalize is true, applies normalize_r_arg_ident to strip leading underscores.

Returns parameter names in declaration order.