message: Add shortcuts for beginning / end of composer
  This adds Ctrl/Command+Home/End shortcuts for jumping to the start and end of
  the composer contents.
  Fixes
diff: @@ -392,6 +392,20 @@ export default class BasicMessageEditor extends React.Component {
  } else if (event.key === Key.ENTER && (event.shiftKey || (IS_MAC && event.altKey))) {
  this._insertText("\n");
  handled = true;
  + // move selection to start of composer
  + } else if (modKey && event.key === Key.HOME) {
  + setSelection(this._editorRef, model, {
  + index: 0,
  + offset: 0,
  + });
  + handled = true;
  + // move selection to end of composer
  + } else if (modKey && event.key === Key.END) {
  + setSelection(this._editorRef, model, {
  + index: model.parts.length - 1,
  + offset: model.parts[model.parts.length - 1].text.length,
  + });
  + handled = true;
  // autocomplete or enter to send below shouldn't have any modifier keys pressed.
  } else {
  const metaOrAltPressed = event.metaKey || event.altKey;
  