feat: Add "Pin selected notes" button to editor title bar (#760)

app/assets/javascripts/components/PinNoteButton.tsx

@@ -0,0 +1,38 @@
+import { AppState } from '@/ui_models/app_state';
+import VisuallyHidden from '@reach/visually-hidden';
+import { observer } from 'mobx-react-lite';
+import { FunctionComponent } from 'preact';
+import { Icon } from './Icon';
+import { toDirective } from './utils';
+
+type Props = {
+  appState: AppState;
+  className?: string;
+};
+
+export const PinNoteButton: FunctionComponent<Props> = observer(
+  ({ appState, className = '' }) => {
+    const notes = Object.values(appState.notes.selectedNotes);
+    const pinned = notes.some((note) => note.pinned);
+
+    const togglePinned = () => {
+      if (!pinned) {
+        appState.notes.setPinSelectedNotes(true);
+      } else {
+        appState.notes.setPinSelectedNotes(false);
+      }
+    };
+
+    return (
+      <button
+        className={`sn-icon-button ${pinned ? 'toggled' : ''} ${className}`}
+        onClick={togglePinned}
+      >
+        <VisuallyHidden>Pin selected notes</VisuallyHidden>
+        <Icon type="pin" className="block" />
+      </button>
+    );
+  }
+);
+
+export const PinNoteButtonDirective = toDirective<Props>(PinNoteButton);