USWDS-Site - Feature: Use banner element

[mejiaj]

Problem

Things we need to know

1. How easy it is to use USWDS Banner element from @uswds/elements package on the site
2. What changes are needed to the component for greater compatibility

Definition of done

1. We're able to add the default banner to the site
2. We can customize the component to match existing implementation
3. We've document the known limitations