Add a delay parameter to snapshotWithOptions

[mykeels]

storybook/addons/storyshots/storyshots-core/src/test-bodies.ts

Line 12 in 7064642

options: { renderer?: any; serializer?: any } | Function = {}

When rendering snapshots for a component, I found that the snapshots were of the loading state of the component, and adding a small delay (10ms) could mean the difference between the snapshot containing the loading or loaded state of the component.

By adding an optional delay?: number parameter to this function, the developer can specify how long such a wait should be before the snapshot is taken.

If this idea is accepted, I'm happy to work on the PR.