Modify the Epic screen to include a custom button

In the Epic view , we want to add a custom button “Contact XYZ Backend”. On the click on this button , a popup opens which will take two inputs from the user. The popup will have two buttons “Submit” and “Cancel”. On click of submit , the popup needs to make an HTTPS call to REST endpoint and submit the user input, the external backend will provide a response that needs to be displayed on the next screen. Once the User confirms the data in response, a button will be present to create Jira story, on click of which a story will be generated.