Font provider not implemented

[ghost]

GMS contains a font provider used to provide fonts commonly available at fonts.google.com, along with Google's non-free Google Sans font. microG does not implement this provider, causing several applications requiring such fonts to display, at best, in an irregular manner.

Here's an example of a font-familly making use of this provider:

<font-family
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:fontProviderAuthority="com.google.android.gms.fonts"
    android:fontProviderCerts="[font-provider-certificates]"
    android:fontProviderPackage="com.google.android.gms"
    android:fontProviderQuery="Google Sans"
    app:fontProviderAuthority="com.google.android.gms.fonts"
    app:fontProviderCerts="[font-provider-certificates]"
    app:fontProviderPackage="com.google.android.gms"
    app:fontProviderQuery="Google Sans"
    tools:ignore="FontValidationError,FontValidationWarning,UnusedAttribute" />

[CoelacanthusHex]

https://github.com/microg/GmsCore/releases/tag/v0.2.20.212158 add dummy
API, but no actual function.

[paolo-caroni]

          I'm reopening this, cause the feature is not fully implemented - it doesn't actually provide fonts and various font weights, but just fallbacks to Roboto Regular. Probably can be improved, but works for not having apps crash, thanks to @grote :)

Originally posted by @mar-v-in in #1097 (comment)

It seems that there is a fallback function for only one font style... but better than a dummy function. Also I think that this issue is a older "duplicated" that should be closed.