cronet_http: depend on org.chromium.net:cronet-api instead

[kmod-midori]

The current implementation depends on com.google.android.gms:play-services-cronet, which pulls in the Google Play services. This might be undesirable for apps that do not want to have GMS code in them (and those who mainly target Chinese users and do not have GMS available).

We should depend on Chromium's API package, which will find the relevant dependencies automatically if they are declared. Additional documentations should be provided to the users on how to choose a Cronet provider (similar to https://exoplayer.dev/network-stacks.html#cronet).