`Path`: make content field `pub` again

Upgrading to the beta and this seems to have changed from `3.3.5` but no reason is given in #1894 for the change so I presume it was a mistake. The content field of `Json` is still `pub` which supports this conclusion.

I recently switched from calling `.into_inner()` to destructuring in the function arguments and it's a lot nicer, especially for singular path arguments such as:

```rust
#[get("/user/{id}")]
async fn get_user(Path(user_id): Path<Uuid>) -> Option<User> {
    // ...
}
```

src/types/path.rs

@@ -46,7 +46,7 @@ use crate::{dev::Payload, error::PathError, FromRequest, HttpRequest};
 /// }
 /// ```
 #[derive(PartialEq, Eq, PartialOrd, Ord, Debug)]
-pub struct Path<T>(T);
+pub struct Path<T>(pub T);
 
 impl<T> Path<T> {
     /// Unwrap into inner `T` value.