fix(napi-derive): tuple object and enum

[CPunisher]

Currently tuple object is broken. For example:

#[napi(object)]
pub struct B(pub u32);

The expanded code contains:

let Self(arg 0) = val; // unexpected whitespace

According to the docs https://docs.rs/quote/latest/quote/macro.quote.html#constructing-identifiers, concatenating two tokens will continue to be two separate tokens.

There is also weird arg#1 in the code. Could it be a typo?