fix(env): improve env detection compatibility for Node

The React Native test environment *is* Node but sets up a window global: https://github.com/facebook/react-native/blob/7a85b911254dbae9fac4c6d8a862a20c33e0b36a/packages/react-native/Libraries/Core/setUpGlobals.js#L18

Reintroduce the navigator.userAgent check as a fallback for detecting a Node environment

src/core/env.ts

@@ -37,7 +37,7 @@ else if (typeof document === 'undefined' && typeof self !== 'undefined') {
     // In worker
     env.worker = true;
 }
-else if (!env.hasGlobalWindow || 'Deno' in window) {
+else if (!env.hasGlobalWindow || 'Deno' in window || (navigator?.userAgent?.indexOf('Node.js') === 0)) {
     // In node
     env.node = true;
     env.svgSupported = true;