Sample bundle for OAuth20 Verify AccessToken flow

### Commit [b6374b3]:
1. Add a sample bundle for OAuth20 Verify AccessToken flow to access a protected resource
2. The invoke script is crafted such that it gives provision for the user to follow any of the grant_type to generate AccessToken, and the generated accesstoken will be used in the verification flow.
3. It implements ratelimiting also
4. No assign message policy to classify the request will be seen, as the Proxy details are embedded inside the ApiProducts, so that the request will be automatically classified based on the Proxy details given in the ApiProduct.