feat: custom timeout and contextTimeout flag in response

[nityanandagohain]

Fixes #4021

Custom timeout can be set by setting the timeout header.
timeout:120
Added it in header as I don't want to unmarshal the payload in middleware.

If context timeout occurs, the response looks like

{
    "status": "success",
    "data": {
        "contextTimeout": true,
        "contexTimeoutMessage": "Result might contain incomplete data due to context timeout, set timeout header for setting custom timeout in seconds eg:- timeout:120",
        "resultType": "",
        "result": [
 .........

let me know if you have any suggestions.