Add official support for Android apps on ChromeOS / Chromebooks

We were surprised to learn in this comment that currently ChromeOS is not officially supported by Qt for Android.

Most ChromeOS devices such as Chromebooks officially support Android apps, and Android apps available via Google Play will be default be available on ChromeOS devices as well. Given the large market share of Chromebooks in some user segments it is highly desirable for Qt to officially support ChromeOS.

While there is no official support by Qt, I’d like to note that our Qt app generally works fine on ChromeOS devices in our testing (except for QTBUG-115012). Adding official support in Qt might mainly require adding ChromeOS devices to the internal testing matrix.