Add a handy way to screenshot the viewport

[sipayRT]

Contribution

• [ ] I'd be willing to implement this feature (contributing guide)

Describe the user story

for now for testing viewport view you need to composite options for assertView command:

await browser.assertView('check-viewport', 'body', {
    allowViewportOverflow: true,
    compositeImage: false
});

Describe the solution you'd like

There must be a more convenient way. For example, a new command with a preset from the example above

await browser.assertViewViewport('check-viewport'); // the command name is discussable

Describe the drawbacks of your solution

No response

Describe alternatives you've considered

No response