Add 6Sense API to navigation project

What is changing in this MR?

1. Replacing Demandbase with 6sense in the navigation project (affects the Solutions dropdown sort order and Resources dropdown right-side featured content)
2. Created 6Sense API token: (https://gitlab.abm.6sense.com/settings/integration/apitokenmanagement) and placed it in the Navigation project > CI/CD > Variables
3. If a user's company size is captured, SMB will be shown for companies with 100 or less employees or shown the mid-market/enterprise content for 101+ employees

Testing

1. Pull down branch locally
2. Create .env file with the 6Sense key and value matching the CI/CD variable
3. You can now console log the API call response to get the response data
4. Hover over Solutions to view the nav dropdown. As a GitLab employee (mid-market/enterprise) , the By Company Size order should be Enterprise, Small Business, Startup
5. Hover over Resources to view the nav dropdown. As a GitLab employee, the far right card should show Lockheed Martin

Go into the Navigation.vue and find the if function at line 63. Change the <= to >=

1. The Solutions dropdown should now show the order as: Small Business, Enterprise, Startups
2. The Resources dropdown should now show the Fullsave customer card

Related to buyer-experience#2457 (closed)