hello_egui v0.4.0 - improvements to egui_inbox, egui 0.27.0

• update all crates for egui 0.27 support
• changes from egui_inbox:

  • egui_inbox now can be used without egui

    • There is a new trait AsRequestRepaint, which can be implemented for anything that can request a repaint
    • Breaking: new_with_ctx now takes a reference to the context
    • Breaking: read_without_ui and replace_without_ui have been renamed to read_without_ctx and replace_without_ctx
    • All other methods now take a impl AsRequestRepaint instead of a &Ui
      but this should not break existing code. A benefit is that you can also
      call the methods with a &Context instead of a &Ui now.

  • Added async and tokio features that add the following:

    • UiInbox::spawn to conveniently spawn a task that will be cancelled when the inbox is dropped.
    • UiInbox::spawn_detached to spawn a task that will not be cancelled when the inbox is dropped.