Prioritise types in prelude over items from a `#[doc(hidden)]` module

[xd009642]

I was passing in a usize instead of an Option<usize> in some of my code and when I ran cargo +nightly check I got this output:

error[E0308]: mismatched types
  --> src/process_handling/linux.rs:59:53
   |
59 |                 execute_test(test, ignored, config, cpus)?;
   |                                                     ^^^^ expected enum `std::option::Option`, found `usize`
   |
   = note: expected enum `std::option::Option<usize>`
              found type `usize`
help: try wrapping the expression in `syn::__private::Some`
   |
59 |                 execute_test(test, ignored, config, syn::__private::Some(cpus))?;
   |                                                     +++++++++++++++++++++    +

For more information about this error, try `rustc --explain E0308`.
error: could not compile `cargo-tarpaulin` due to previous error

I'm on the latest nightly and mentioned it on a rust discord and @memoryruins pointed me to the RA issue rust-lang/rust-analyzer#8511 and then realised there didn't seem to be a rustc issue for it so I'm raising it now 👀

[In-line]

This PR fixes it #87349 just didn't have enough time recently to finish it.