Fix compose form submission reloading web interface (#19762)

* Fix compose form submission reloading web interface

Fix regression introduced by #19742

* Fix various compose form buttons being handled like submit buttons

* Fix coding style issue

* Fix missing onClick prop check

app/javascript/mastodon/components/icon_button.js

@@ -141,6 +141,7 @@ export default class IconButton extends React.PureComponent {
 
     return (
       <button
+        type='button'
         aria-label={title}
         aria-pressed={pressed}
         aria-expanded={expanded}