Auto merge of #17141 - MortimerGoro:android_fonts, r=mbrubeck

Ged rid of libfontconfig in Android

Libfontconfig dependency is causing huge startup times in Android (20 seconds on each page load!). On other platforms fontconfig caches are already available or can be prebuilt on installation scripts, but this can't be done on Android. Updating libfontconfig dependency doesn't fix the problem either.

This PR gets rid of libfontconfig in Android. It queries available fonts and variations from Android System font configuration files. Android doesn't provide an API to query system fonts until Android O (which is very far from the minimum API right now...)

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- [ ] These changes fix #16195 (github issue number if applicable).

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