fix: support custom variable names in expo-font-loaded-check

[danielchen0]

Summary

• The expo-font-loaded-check rule previously only matched the exact variable name loaded
• Now it tracks the actual destructured variable name from useFonts() (e.g. fontsLoaded)
• Patterns like if (!fontsLoaded && !fontError) return null are now correctly recognized

Example

// This was incorrectly flagged before:
const [fontsLoaded, fontError] = useFonts({ Inter_400Regular });
if (!fontsLoaded && !fontError) return null;