SSR Components missing default size="1em"
TL;DR: I believe the following line of code should change from `size,` to `size = "1em",`
https://github.com/phosphor-icons/react/blob/master/src/lib/SSRBase.tsx#L12

---
A very common pattern is that we have, is that we want our icons to follow the text font size, which works great for client components, since their width/height defaults to `1em`. For example (using tailwind classes)

```jsx
<a className="text-2xl" href="/docs">
  <ArrowRight />
  Go to Documentation
</a>
```

This does not work as expected for SSR components, because by default, they do not have width/height set to 1em.

I understand that the components fom `dist/ssr` are not using React Context, but we should still have the same sensible defaults even for SSR (something that we have for `color` and `weight`), but just not be able to change them, because we cant use context.
