Reexport older versions of raw-window-handle

When the user decides to use an older version of raw-window-handle,
through the rwh_04 or rwh_05 features, it makes sense to reexport the
crate so they don’t have to depend on it manually and can instead use
winit::raw_window_handle.

src/changelog/unreleased.md

@@ -40,6 +40,10 @@ changelog entry.
 
 ## Unreleased
 
+### Added
+
+- Reexport `raw-window-handle` versions 0.4 and 0.5 as `raw_window_handle_04` and `raw_window_handle_05`.
+
 ### Fixed
 
 - On macOS, fix panic on exit when dropping windows outside the event loop.