The DisplayUtils is using deprecated functions for calculating the display size, since Android 11, the Android team introduced the notion of WindowMetrics to account for the aspect of resizability of windows in Android in the future, this new API should offer more accurate results, and allow taking the insets (system bars) into account when calculating it.

The change I did here uses the default value returned by getCurrentWindowMetrics without excluding the insets, as it's same as what getDefaultDisplay is giving, in the future, we can decide if we want to update it.

I also included another change, the API currently has two methods called getDisplayPixelWidth, one of them needs a Context, and the other one doesn't, but the real issue is that they give different results when the screen is split, since one will return the actual size of the display, while the one accepting Context will return the size of the app's window, so I renamed the functions a bit to make it clear to getWindowPixelWidth and getWindowPixelHeight.
I deprecated the other ones to avoid breaking anything, but I wonder if this is the right move, or should we remove them and update the clients right away, WDYT?

For testing, please refer to the PR woocommerce/woocommerce-android#5346