Allow per-snapshot configuration of discovery.networkIdleTimeout about cli HOT 2 OPEN

Currently, there isn't a way if you're using percy exec -- based SDK

though if you're using percy snapshot ... there is a workaround where you can pass in execute function OR waitForTimeout which would be executed before taking snapshot.

serve: './'

snapshots:
- name: sample snapshot
  url: /sample.html
  widths: [1280]
  waitForTimeout: 2000
  execute: |
    async () => {
        function sleep(time) {
          return new Promise((resolve) => setTimeout(resolve, time));
        }
        await sleep(2000);
    }

from cli.

we'd be happy to receive a PR, it will require change here - ref { and associated readme and tests)

we'll need to add networkIdleTimeout entry there, post which we can pass like below to make it work

with percy snapshot ...

serve: './'

snapshots:
- name: sample snapshot
  url: /sample.html
  widths: [1280]
  discovery:
    networkIdleTimeout: 500

or if using percy exec ...

await percySnapshot(page, 'sample snapshot', {
   discovery: {
    networkIdleTimeout: 500
   }
});

from cli.