Requirements

open-feature/flagd-schemas#183 deprecated the GetMetadata call. Now the sync stream can return the same data, saving providers an RPC call. Providers will do exactly the same thing with this information as they currently do with the GetMetadata call.

Requirements:

• implement sync_context field in SyncFlags, which has the same payload as GetMetadata
• keep GetMetadata for now, for reverse compatibility
• add associated tests