Support declarative response delays

[diego-aquino]

Users currently can implement response delays by using a computed response handler:

const handler = interceptor
  .get('/users')
  .respond(async () => {
    await new Promise((resolve) => setTimeout(resolve, 1000))
    return { status: 200, body: [] } 
  })

We could also allow declarative delays.

Proposal

A new handler method to declare a fixed or ranged delay. If a range is provided, a random value is selected within that interval.

const handler = interceptor
  .get('/users')
  .delay(200) // a fixed delay of 200ms will be used for each request
  .respond({ status: 200, body: [] })
// ...

const handler = interceptor
  .get('/users')
  .delay((request) => {
    return request.url.includes('slow=true') ? { min: 200, max: 1000 } : 0
  })
  .respond({ status: 200, body: [] })
// ...

Providing a way to use default delays per interceptor and for all interceptors is also a good idea.