Add null check before calling fabricSuspendOnActiveViewTransition (#3… (opens in new tab)

Add null check before calling fabricSuspendOnActiveViewTransition \(\#36310\) \#\# Summary - Adds a null check before calling \`fabricSuspendOnActiveViewTransition\(\)\` in the Fabric renderer's \`suspendOnActiveViewTransition\` export - Prevents crashes on hosts where \`nativeFabricUIManager\` does not yet implement \`suspendOnActiveViewTransition\` \#\# Test plan - Verified the change compiles correctly - Hosts with \`suspendOnActiveViewTransition\` implemented continue to work as before - ...