[invoke/verifyState] Add optional `accountLinkingUrl` return type for invoke

To support a change in the Teams FE, we need to optionally allow developers to configure a static account linking url that, if present, would be returned to the Teams Platform after processing of the activity.

Platform Code:
https://skype.visualstudio.com/SCC/_git/async_messaging_botapiservice/pullrequest/1264762?_a=files#:~:text=var%20obj%20%3D%20JToken,string)obj%3F%5B%22accountLinkingUrl%22%5D%3B

Verify State Response Type:
https://github.com/microsoft/teams.ts/blob/main/packages/api/src/models/invoke-response.ts#L61

Sample:

```typescript
new App({
oauth: {
accountLinkingUrl: '...'
}
});
```

Start with the Verify State response type in packages/api/src/models/invoke-response.ts and trace how the App oauth configuration is processed for invoke activities. Add optional accountLinkingUrl support so a configured static URL is returned to the Teams Platform after processing; verify that it remains optional when not configured.

Written by the indexing model from the issue text.