app,widget: implement Editor IME support, add Android implementation

Fixes: https://todo.sr.ht/~eliasnaur/gio/116
References: https://todo.sr.ht/~eliasnaur/gio/246
Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/os_js.go

@@ -300,7 +300,7 @@ func (w *window) addHistory() {
 func (w *window) flushInput() {
 	val := w.tarea.Get("value").String()
 	w.tarea.Set("value", "")
-	w.w.Event(key.EditEvent{Text: string(val)})
+	w.w.EditorInsert(string(val))
 }
 
 func (w *window) blur() {
@@ -481,6 +481,8 @@ func (w *window) animCallback() {
 	}
 }
 
+func (w *window) EditorStateChanged(old, new editorState) {}
+
 func (w *window) SetAnimating(anim bool) {
 	w.animating = anim
 	if anim && !w.animRequested {