Position persistence and sane clamping to still-available monitors for Windows (#2583)

* Attempt to fix monitor clamping on Windows so window positions can be restored between sessions.

* Missed a change.

* Renamed variables, reorganized some lines of code, and added some more comments.

* Cargo fmt run

* Updated CHANGELOG.md to briefly describe my change

* Updated CHANGELOG.md to briefly describe my change

* Applied suggested fixes from emilk
Discovered an issue where putting the monitor off a non-primary monitor to the left causes the position to be off the monitor x and y range, clamping to the primary instead of the non-primary.

* Fix for matching negative restored window positions. Should clamp if any part of the window had been visible on a remaining monitor.

* Apparently compiler attributes on statements have been marked unstable.
Rather than just wrap in blocks, I kind of prefer the more explicit if cfg! call for line 114.

CHANGELOG.md - correct a missing paren I noticed

* I was being silly, I don't need to clone inner_size_points on line 112

* Cargo fmt run

* Update crates/egui-winit/CHANGELOG.md

emilk suggested changelog formatting

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

* Update window_settings.rs

Satisfy CI Error

* clippy

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/eframe/src/native/epi_integration.rs

@@ -108,6 +108,8 @@ pub fn build_window<E>(
     let inner_size_points = if let Some(mut window_settings) = window_settings {
         // Restore pos/size from previous session
         window_settings.clamp_to_sane_values(largest_monitor_point_size(event_loop));
+        #[cfg(windows)]
+        window_settings.clamp_window_to_sane_position(&event_loop);
         window_builder = window_settings.initialize_window(window_builder);
         window_settings.inner_size_points()
     } else {