input-method-experimental: Implement actions

[dcz-self]

Upstream protocol merged in https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/433 .

Testing procedure described there and in the demo input method. Requirements copied for convenience:

Use anvil from https://github.com/dcz-self/smithay/tree/actions

Start anvil:

git clone https://github.com/dcz-self/smithay
git checkout origin/actions
cd smithay/anvil
cargo run --winit

The demo application is the winit example program. Use winit from

git clone https://github.com/dcz-self/winit
git checkout origin/actions
cd winit
WAYLAND_DISPLAY=wayland-1 cargo run --example ime

[PolyMeilex]

Thanks