fix(router): Drawer layout incorrect position on initial load

[marklawlor]

Why

expo/router#837

ExpoRouter provides a SafeAreaContextProvider with an initial value of 0 for all dimensions. The drawer layout uses these dimensions to calculate the necessary x offset for its 'closed' state. These calculations assume a minimum screen size, so having 0 caused it to initially render on the screen

How

We only need these initial values for static rendering, so now we only provide them when rendering SSR.

Test Plan

Tested manually by creating a new project.

Checklist

• Documentation is up to date to reflect these changes (eg: https://docs.expo.dev and README.md).
• Conforms with the Documentation Writing Style Guide
• This diff will work correctly for npx expo prebuild & EAS Build (eg: updated a module plugin).