Update shadows with new design token shadows

[georgewrmarshall]

Description

Shadow tokens were recently merged into the design token repo and released in v1.8. Update the design tokens package and all of the shadows in the app to use the new tokens

Technical Details

• Update @metamask/design-tokens to v^1.8.0
• Update all components that use shadow to use the design tokens

Acceptance Criteria

• All shadows in the app use the design tokens unless absolutely necessary

References

• @metamask/design-tokens repo
• storybook design token shadow documentation