UX: improved collapsed drawer state/interactions (#29850)

- Clicking the channel title of a collapsed drawer will only open the drawer, and not open settings
- Remove the back button when the drawer is collapsed
- Uses same icon for toggling on chat that composer
- add max-width to minimised drawer + add hover effect
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Co-authored-by: chapoi <101828855+chapoi@users.noreply.github.com>

app/assets/javascripts/discourse/app/components/composer-toggles.js

@@ -29,13 +29,13 @@ export default class ComposerToggles extends Component {
   toggleIcon(composeState) {
     return composeState === "draft" || composeState === "saving"
       ? "xmark"
-      : "chevron-down";
+      : "angles-down";
   }
 
   @discourseComputed("composeState")
   fullscreenIcon(composeState) {
     return composeState === "draft"
-      ? "chevron-up"
+      ? "angles-up"
       : composeState === "fullscreen"
       ? "discourse-compress"
       : "discourse-expand";