add action set icon while running (#1590)

* set windows icon live action

* change get icon to insto raw

* remove mobile docs

* format

* fix format

* add file methods to Icon

* Rename action to `ChangeIcon` and tidy up `Icon` modules

* Fix documentation of `icon::Error`

* Remove unnecessary `\` in `icon` documentation

* Remove `etc.` from `Icon` documentation

---------

Co-authored-by: Héctor Ramón Jiménez <hector0193@gmail.com>

winit/src/application.rs

@@ -770,6 +770,9 @@ pub fn run_command<A, E>(
                         mode,
                     ));
                 }
+                window::Action::ChangeIcon(icon) => {
+                    window.set_window_icon(conversion::icon(icon))
+                }
                 window::Action::FetchMode(tag) => {
                     let mode = if window.is_visible().unwrap_or(true) {
                         conversion::mode(window.fullscreen())