feat: Allow SignInButton to accept all normal button props

[tinaszheng]

What is the feature you would like to implement?
I'd like to pass in default button props, like id, ref, or className to the SignInButton component. One use case is I'd like to programmatically click the button to show the sign in flow without needing the user to click themselves, or pass in tailwind-style styling to the button.

[joeblau]

The challenge with this is that SignInButton is more than just a button. It's the button, the QR code, the modal header, the button on the QR code, the style of the modal and a bunch of other stuff.

I think having a nice JSX template where we can modify all of the components would be a great way to go.