Fabric Extensibility Toolkit - Workload Development Kit Migration support

The Fabric Extensibility Toolkit (FET) now provides migration support from the Workload Development Kit (WDK), enabling developers to transition existing workloads to the modern FET platform with minimal friction. This capability ensures continuity for solutions built on WDK while unlocking advanced features. Migration guidance includes documentation, and best practices to streamline the process -- from updating manifest versions to adopting new APIs and SDKs.