windows: Fix cursor style not changing when hovering over items in the title bar (#22580)

Closes #22578

Currently, the `hovered` boolean in the window state is only updated by
the `WM_MOUSELEAVE` event, which fires when the mouse cursor leaves the
window's working area. This means that when the user moves the cursor
from the window to the title bar, `hovered` is set to `false`. Later in
the code, this flag is used to determine the cursor style and check if
the cursor is over the correct window.

The `hovered` boolean should remain active even when the mouse is over
non-client items, such as the title bar or window borders. This PR fixes
that by using `WM_NCMOUSELEAVE` event, which is triggered when the mouse
leaves non-client items. This event is used to update the `hovered`
boolean accordingly.

Now, `hovered` is `true` when the mouse is over the window's working
area, as well as non-client areas like the title bar.

More context:

- Existing: `dwFlags: TME_LEAVE` tracks window area mouse leaves, which
is used in `handle_mouse_move_msg` func.
- New: `dwFlags: TME_LEAVE | TME_NONCLIENT` tracks non-client mouse
leaves, which is used in `handle_nc_mouse_move_msg` func.

Preview:


https://github.com/user-attachments/assets/b319303f-81b9-45cb-bf0c-535a59b96561

Release Notes:

- Fix cursor style not changing on hover over items in the title bar on
Windows