[core] mergeReactProps cannot merge non-native event handlers

[mj12albert]

Sandbox: https://codesandbox.io/p/sandbox/fervent-chaplygin-779dcw

Click the toggle and it will throw: Uncaught TypeError: Cannot create property 'preventBaseUIHandler' on boolean 'true'

<Tooltip.Trigger
  render={
    <Toggle
      pressed={isPressed}
      onPressedChange={(nextPressed) => {
        setPressed(nextPressed);
      }}
    >
      <Icon />
    </Toggle>
  }
/>

The uncontrolled counterpart of this works: https://codesandbox.io/p/sandbox/epic-hofstadter-62pnf3

The issue is that mergeReactProps expects the event as the first argument like native handlers, but our custom handlers usually pass event as the second: https://github.com/mui/base-ui/blob/master/packages/react/src/utils/mergeReactProps.ts#L44

[atomiks]

This is also the case with e.g. motion events, although my solution here assumes it's an object which is also not enough:

https://github.com/mui/base-ui/pull/1236/files#diff-9c898048e86d277b9a0100de67d4d51e04b4c64bfed6c5412e6cb537ebaab3f1L52-R57