android_main() now takes an `app: AndroidApp` argument and has an
extern "Rust" ABI instead of "C" ABI.
This should help make it possible to run multiple native Activities in a
single process.
The functionality found in egui_winit_platform and egui_wgpu_backend is
now available in the upstream egui-winit and egui-wgpu crates
respectively.
This has simplified the example itself and also removed the dependency
on epi.
The example is now based on egui 0.18 (was previously 0.17)
Since the upstream egui-winit/wgpu crates were generally assuming that
the graphics context and surface can be initialized immediately this
currently builds against a branch that aims to upstream changes that
remove these assumptions:
https://github.com/rib/egui/tree/android-deferred-winit-wgpu
Ref: https://github.com/emilk/egui/pull/1634
Robert Bragg