[LTC] Inherits LazyGraphExecutor (#4296)
Summary:
This patch lets XLAGraphExecutor inherits LazyGraphExecutor. A few things worth noting:
1. It replaces xla::util::ExceptionCleanup with torch::lazy::ExceptionCleanup.
2. It uses upstream SyncTensorsConfig, SyncTensorCollection, and PostOrderData.
Test Plan:
CI.
