Add `app_id` to `bevy::window::Window`

[VitalyAnkh]

Objective

• Fixes #4188, make users could set application ID for bevy apps.

Solution

• Add app_id to bevy::window::Window, which will make bevy call winit::platform::wayland::WindowBuilderExtWayland::with_name() or winit::platform::x11::WindowBuilderExtX11::with_name() when building the window, then the window will have a desired "application ID" property.

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Changelog

Added

• Add app_id to bevy::window::Window.

Migration Guide

• Set the bevy_window::Window's app_id:

App::new()
        .add_plugins(DefaultPlugins.set(WindowPlugin {
            primary_window: Some(Window {
                title: "I am a window!".into(),
                app_id: "SpaceShooter.SpaceGameCompany".into(),
                resolution: (500., 300.).into(),
                ..default()
            }),
            ..default()
        }))
        .run();

[mockersf]

is it an issue to have both x11 and wayland features enabled, and have both methods called?

[deifactor]

is it an issue to have both x11 and wayland features enabled, and have both methods called?

From looking at the winit code, no: both of them set platform_specific.name in the same way.

[VitalyAnkh]

I'm very sorry for such a long delay! After almost a year, I finally remembered this PR. I've rebased it onto the latest bevy and updated some documentation. The concept of application ID or wm_class is only applicable to UNIX platforms, and currently, winit does not provide a way to modify it after the app has started. This feature is quite for many window managers to manage windows. Please review the current code again, thank you very much!

[musjj]

The concept of application ID or wm_class is only applicable to UNIX platforms

The equivalent of this on Windows is window class names, which winit also supports:

with_class_name

[VitalyAnkh]

@musjj Thanks! Didn't find this before. I will update this patch ASAP.