Add MongoDB Schema Validation

[tushar821999]

Add isURL validation for inputURL and outputURL in Models->urls.js using Validator,js.

{
"_id": "60b65180e14f372af0e298bb",
"inputURL": "https://somerandomurl.com/this-is-my-first-api-call-which-i-need-to-explain",
"inputText": "api-call",
"outputText": "localhost:3000/api-call",
"__v": 0
}