Fix InputOptions doc-link to SessionUi::input

The UI-grouping commit f4aa8d9 moved input/select/confirm/elicitation off
Session into SessionUi, but the rustdoc on InputOptions still referenced
the old crate::session::Session::input path. Cargo doc with
-D rustdoc::broken_intra_doc_links rejected the link.

Repoints the link to crate::session::SessionUi::input.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: tclem

rust/src/types.rs

@@ -2183,7 +2183,7 @@ pub struct UiCapabilities {
     pub elicitation: Option<bool>,
 }
 
-/// Options for the [`Session::input`](crate::session::Session::input) convenience method.
+/// Options for the [`SessionUi::input`](crate::session::SessionUi::input) convenience method.
 #[derive(Debug, Clone, Default)]
 pub struct InputOptions<'a> {
     /// Title label for the input field.