Iris: CurrTimeMS in FReplicationReader::ResolveAndDispatchUnresolvedReferences saturates on ARM64, so unresolved handles never move to the cold cache

In FReplicationReader::ResolveAndDispatchUnresolvedReferences, CurrTimeMS is computed as static_cast<uint32>(FPlatformTime::Seconds() * 1000.0f). FPlatformTime::Seconds() includes GetSecondsTimeOffset() (16777216.0 on Apple and Windows), so the value always exceeds UINT32_MAX and the conversion is undefined behaviour. x64 happens to wrap, but ARM64 saturates to 0xFFFFFFFF. As a result, handles never move from HotUnresolvedHandleCache to ColdUnresolvedHandleCache and are retried on every call.

1. Run an Iris client on an ARM64 platform.
2. Replicate an object holding a reference that stays unresolved longer than net.Iris.HotResolvingLifetimeMS.
3. Observe that the handle never moves from HotUnresolvedHandleCache to ColdUnresolvedHandleCache (CurrTimeMS is always 0xFFFFFFFF).