…on Windows

First off, I don't think there was any need for the repeated checks for device pixel ratio changes via checkContentScale because we should be able to rely on the graphicsContextScaleTransform property from AWT.

I removed the corresponding code and changed contentScale to directly return the platform-specific implementations from the toolkit/device. There's also no need to cache the value because the device and the graphics configuration already does it for us.

Secondly, there was a layout glitch on Windows when moving windows between monitors with different device pixel ratios. A fix has to happen directly in the JBR, but for now I created a semi-cheap workaround. See this issue and the linked ones for details: https://youtrack.jetbrains.com/issue/JBR-5259/Canvas-is-painted-at-the-wrong-position-after-dragging-JFrame-to-a-monitor-with-different-scale