macOS: virtual keycode(Backslash) when keyDown event in JIS keyboard layout

[Joseph0304]

• Tested on all platforms changed
• Added an entry to CHANGELOG.md if knowledge of this change could be valuable to users
• Updated documentation to reflect any user-facing changes, including notes of platform-specific behavior
• Created or updated an example program if it would help users understand this functionality
• Updated feature matrix, if new features were added or implemented

Fix example: #2577
I tried to fix it, but unable to get keycode(backslash) on keyUp event.
Test $ cargo run --example ime

...
TRACE [winit::platform_impl::platform::view] Triggered `keyDown:`
...
TRACE [winit::platform_impl::platform::view] Completed `keyDown:`
TRACE [winit::platform_impl::platform::view] Triggered `selectedRange`
TRACE [winit::platform_impl::platform::view] Completed `selectedRange`
TRACE [winit::platform_impl::platform::view] Triggered `selectedRange`
TRACE [winit::platform_impl::platform::view] Completed `selectedRange`
key: KeyboardInput { scancode: 93, state: Pressed, virtual_keycode: Some(Backslash), modifiers: (empty) }
ch: '\\'
TRACE [winit::platform_impl::platform::view] Triggered `keyUp:`
TRACE [winit::platform_impl::platform::view] Completed `keyUp:`
key: KeyboardInput { scancode: 93, state: Released, virtual_keycode: Some(Yen), modifiers: (empty) }
...

May be helpful that https://github.com/chromium/chromium/blob/a86a8a6bcfa438fa3ac2eba6f02b3ad1f8e0756f/ui/views/cocoa/bridged_content_view.mm#L541

[kchibisov]

Thanks for attempt, but see #2686 #2662.