Fix action failures due to state tree encoding (#53655)

fixes #53654

### Related PRs
- #51017

packages/next/src/client/components/router-reducer/reducers/server-action-reducer.ts

@@ -52,7 +52,7 @@ async function fetchServerAction(
     headers: {
       Accept: RSC_CONTENT_TYPE_HEADER,
       'Next-Action': actionId,
-      [NEXT_ROUTER_STATE_TREE]: JSON.stringify(state.tree),
+      [NEXT_ROUTER_STATE_TREE]: encodeURIComponent(JSON.stringify(state.tree)),
       ...(process.env.__NEXT_ACTIONS_DEPLOYMENT_ID &&
       process.env.NEXT_DEPLOYMENT_ID
         ? {

test/e2e/app-dir/actions/app-action.test.ts

@@ -393,6 +393,16 @@ createNextDescribe(
           return newTestCookie !== currentTestCookie ? 'success' : 'failure'
         }, 'success')
       })
+
+      it('should handle unicode search params', async () => {
+        const browser = await next.browser('/server?name=名')
+
+        const cnt = await browser.elementByCss('h1').text()
+        expect(cnt).toBe('0')
+
+        await browser.elementByCss('#inc').click()
+        await check(() => browser.elementByCss('h1').text(), '1')
+      })
     })
 
     describe('fetch actions', () => {