USWDS - Feature: Aria-hide lock icon and flag in banner

Is your feature request related to a problem? Please describe.

There are some graphical elements in the banner that are purely visual and add unnecessary content for screenreaders.

Describe the solution you'd like

The lock icon and surrounding parentheses can be made aria-hidden, as it only communicates visual information. https://github.com/uswds/uswds/blob/aa119d40aed62395bf36adf711dd3a1b0625337e/packages/usa-banner/src/usa-banner.twig#L39

Ditto for the flag image, which is purely decorative: https://github.com/uswds/uswds/blob/aa119d40aed62395bf36adf711dd3a1b0625337e/packages/usa-banner/src/usa-banner.twig#L16

Describe alternatives you've considered

No response

Additional context

No response

Code of Conduct

• [X] I agree to follow this project's Code of Conduct.
• [X] I checked the current issues for duplicate feature requests.