feat(WWP-3314): add usnat config to consent

[kboeff]

https://nidigitalsolutions.jira.com/browse/WWP-3314

What

Background - why this is needed - Multi-State Privacy Agreement/String (MSPA) is a signal that notifies downstream partners that participating publishers have provided end-users with specific notice and choice over data processing activities on their properties. The Multi State Privacy Agreement is now available to implement on our properties alongside the U.S. Privacy String (USPS) with the intention that the MSPS will eventually supplant USPS.

What did you do - Updated Consent component to include the GPP stub file. Updated SP config to accept usnat object. This way both the new GPP string and legacy CCPA string are generated. For backwards compatibility the ccpa object is still available in Consent config.

I have done:

• Written unit tests against changes
• Written functional tests against the component and/or NewsKit site
• Updated relevant documentation

I have tested manually:
The feature's functionality is working as expected on Chrome, Firefox, Safari and Edge
The screen reader reads and flows through the elements as expected.
There are no new errors in the browser console coming from this PR.
When visual test is not added, it renders correctly on different browsers and mobile viewports (Safari, Firefox, small mobile viewport, tablet)
The Playground feature is working as expected
Before:

After:
Using current branch build locally inside wd-web-platform project triggers gpp API correctly. Consent is called with the prop usnat: { includeUspApi: true }.

The cookie value for ccpaUUID is still present.

Who should review this PR:

How to test:
Consent component used with the usnat: { includeUspApi: true } should trigger GPP API as shown above. This is the test function:
__gpp('ping', (pingReturn, success) => {console.log('Ping request was successful: ' + success, pingReturn);});

[pp-serviceaccount]

You can preview these changes on:
Documentation Site: http://ncu-newskit-docs-pr.s3-website-eu-west-1.amazonaws.com/wwp-3314
Storybook: http://ncu-newskit-docs-pr.s3-website-eu-west-1.amazonaws.com/wwp-3314/storybook

[lhaggar]

Checked the docs page and a minor change is needed, but otherwise think it's looking good!