feat: implement getServerResult in persist middleware

this avoids hydration errors when state is restored from e.g. localstorage synchronously

Author: TkDodo

src/middleware/persist.ts

@@ -271,6 +271,8 @@ const oldImpl: PersistImpl = (config, baseOptions) => (set, get, api) => {
     api,
   )
 
+  api.getServerState = () => configResult
+
   // a workaround to solve the issue of not storing rehydrated state in sync storage
   // the set(state) value would be later overridden with initial state by create()
   // to avoid this, we merge the state from localStorage into the initial state.
@@ -425,6 +427,8 @@ const newImpl: PersistImpl = (config, baseOptions) => (set, get, api) => {
     api,
   )
 
+  api.getServerState = () => configResult
+
   // a workaround to solve the issue of not storing rehydrated state in sync storage
   // the set(state) value would be later overridden with initial state by create()
   // to avoid this, we merge the state from localStorage into the initial state.