refactor(snack-runtime): upgrade custom runtime to Expo SDK 50

[byCedric]

Why

This upgrades the snack-runtime and snack-shell projects to the latest Expo SDK 50.0.17.

How

• Synced new EAS Update URL handling
• Added new error state not-found when opening Snacks without channels
• Synced vendored modules from runtime
• Upgraded dependencies and peer dependencies

Test Plan

TBD