Allow specifying `MonitorHandle` when constructing a `Window`

Description

I recently encountered a papercut in egui where my application does not save the last Window it was added to. While looking at how I might implement this feature, I noticed that while the MonitorHandle documentation states:

Allows you to retrieve information about a given monitor and can be used in Window creation.

The WindowAttributes struct used for constructing a Window does not allow you to specify a MonitorHandle in order to control where the monitor is constructed.

I'm unsure if there are technical blockers at play here that prevent this from being possible. For example, someone in the egui discord mentioned that Wayland could possibly be problematic. I'm opening this issue for discussion with intent to later do the work involved.

As an aside I should create a separate issue for this, but it may be nice to have a way to uniquely identify a monitor beyond its name (which may have collisions?).

Relevant platforms

Windows

Start by reviewing the winit MonitorHandle, WindowAttributes, and Window APIs, then inspect the platform behavior relevant to Windows and Wayland. Determine whether a monitor can be specified during window construction across the supported platforms, document any blockers, and define the resulting API behavior before implementation.