Asking for more KeyAction events when using android keyboard.

Description

This issue also concerns the PR https://github.com/rust-mobile/android-activity/pull/178 from @jancespivo

With Openxr/StereoKit-rust, as I can't use neither Window::set_ime_allowed nor app.show_soft_input(), I tested the Android keyboard launched via JNI on the Meta Quest2. It works exactly like any Android device.
https://github.com/mvvvv/StereoKit-rust/blob/master/src/tools/os_api.rs#L191

Winit blocks many characters including accented characters which it replaces completely with a backspace and erases the character typed previously. I made a short video: https://youtu.be/os8cucfF3D8

The problem is that I can only rely on event::ElementState::Pressed and event::ElementState::Released which are the only events retained (https://github.com/rust-windowing/winit/blob/5ea81efc74ebaa04a7cb4621ec522bce14d700e5/src/platform_impl/android/mod.rs#L461) when in the log I can see the events I need:

12-30 15:16:17.601 23830 23830 W ViewRootImpl[NativeActivity]: Dropping event (no window focus):KeyEvent { action=ACTION_DOWN, keyCode=KEYCODE_DEL, scanCode=0, metaState=0, flags=0x0, repeatCount=0, eventTime=0, downTime=0, deviceId=-1, source=0x0, displayId=0 }
12-30 15:16:17.601 23830 23830 W ViewRootImpl[NativeActivity]: Cancelling event (no window focus):KeyEvent { action=ACTION_UP, keyCode=KEYCODE_DEL, scanCode=0, metaState=0, flags=0x20, repeatCount=0, eventTime=0, downTime=0, deviceId=-1, source=0x0, displayId=0 }
12-30 15:16:17.601 23830 23830 W ViewRootImpl[NativeActivity]: Cancelling event (no window focus):KeyEvent { action=ACTION_UP, keyCode=KEYCODE_DEL, scanCode=0, metaState=0, flags=0x20, repeatCount=0, eventTime=0, downTime=0, deviceId=-1, source=0x0, displayId=0 }
12-30 15:16:17.602 23830 23830 W ViewRootImpl[NativeActivity]: Dropping event (no window focus):KeyEvent { action=ACTION_MULTIPLE, keyCode=KEYCODE_UNKNOWN, scanCode=0, characters="ò", metaState=0, flags=0x0, repeatCount=0, eventTime=19026369, downTime=19026369, deviceId=-1, source=0x101, displayId=-1 }
12-30 15:16:17.605 23830 23882 D SK_rust_Demos: !!!KeyboardInput: KeyEvent { physical_key: Code(Backspace), logical_key: Named(Backspace), text: None, location: Standard, state: Released, repeat: false, platform_specific: KeyEventExtra }

Having access to ACTION_MULTIPLE event seems to be the only way to get enhanced characters(here ò), smileys and utf8 characters.

Device and Android version

Meta Quest 2 Horizon OS v72 (android 12.1)

Winit version

0.30.7

Start in platform_impl/android/mod.rs at the event handling around the retained ElementState events, and review PR 178 for the related work. Trace how Android ACTION_MULTIPLE events are currently handled, then verify that accented characters, smileys, and other UTF-8 input can reach the public keyboard events without breaking existing press and release events.