Add Modal Testing to modal.yml (#46796)

Summary:
This pr is part of issue https://github.com/facebook/react-native/issues/46757 solving tasks [ME2E0001] and [ME2E0002].
## Changelog:
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[ Internal ] [ Added ] - Add e2e test for modal

Pull Request resolved: https://github.com/facebook/react-native/pull/46796

Test Plan:
yarn e2e-test-ios
yarn e2e-test-android

Reviewed By: cortinico

Differential Revision: D63829299

Pulled By: cipolleschi

fbshipit-source-id: ff64d0babde8aea6e2586c2f69056a10533750f9

packages/rn-tester/.maestro/modal.yml

@@ -9,3 +9,13 @@ appId: ${APP_ID} # iOS: com.meta.RNTester.localDevelopment | Android: com.facebo
     speed: 60
 - tapOn:
     id: "Modal"
+- assertVisible:
+    text: "Show Modal"
+- tapOn:
+    text: "Show Modal"
+- assertVisible:
+    text: "Close"
+- tapOn:
+    text: "Close"
+- assertVisible:
+    text: "Show Modal"