Convert Rust field names (snake case) to type names (pascal case) using proc_macro2 identifiers.
```rust use procmacrotype_name::ToTypeName;
let ident: procmacro2::Indent = Ident::new("foobar", Span::callsite()); let typeident = (&ident).totypeident(ident.span());
asserteq!(typeident.tostring(), "FooBar".toowned());
quote! { enum #type_ident {} } ```