Reorganize rustdoc tests into their correct subdirectories for better categorization: - Move lint-related tests to rustdoc-ui/lints/ - Move intra-doc link tests to rustdoc-ui/intra-doc/ - Move deref-related tests to rustdoc-ui/deref/ - Move doc-cfg test to rustdoc/doc-cfg/ This improves test organization and makes it easier to find tests related to specific rustdoc functionality.