[DSR] Updated Avatar to use shared types and add hasBorder and hasSolidBackgroundColor

[brianacnguyen]

Description

This PR updates all Avatar-related components to

• use shared types
• have 2 additional props hasBorder and hasSolidBackgroundColor

Related issues

Fixes: #509

Manual testing steps

1. Run yarn storybook from root

Screenshots/Recordings

Before

After

Screen.Recording.2025-03-25.at.10.05.52.AM.mov

Pre-merge author checklist

• I've followed MetaMask Contributor Docs
• I've completed the PR template to the best of my ability
• I’ve included tests if applicable
• I’ve documented my code using JSDoc format if applicable
• I’ve applied the right labels on the PR (see labeling guidelines). Not required for external contributors.

Pre-merge reviewer checklist

• I've manually tested the PR (e.g. pull and build branch, run the app, test code being changed).
• I confirm that this PR addresses all acceptance criteria described in the ticket it closes and includes the necessary testing evidence such as recordings and or screenshots.

[georgewrmarshall]

Thanks for adding these changes. With the latest decision to keep background-muted opaque, it seems like these updates might no longer be needed. Do you think we should close this PR, or is there still a case for keeping it open?