Update Avatar and improve fallback

[FelixTJDietrich]

Description

Motivation

Avatar component was fine but I wanted to try out more complex Angular features.

I was thinking of using directives but I still don't like them.

Key Changes

• Split Avatar into multiple components, app-avatar, app-avatar-image, and app-avatar-fallback
• Fallback can be anything now
• Remove CVA from Avatar since it is not needed, we can also do this for future components that don't need variants
• Also inline the html templates, we can do this for small components

Checklist

General

• [x] PR title is clear and descriptive
• [x] PR description explains the purpose and changes
• [x] Code follows project coding standards
• [x] Self-review of the code has been done
• [x] Changes have been tested locally
• [ ] Screenshots have been attached (if applicable)
• [ ] Documentation has been updated (if applicable)

Client (if applicable)

• [x] UI changes look good on all screen sizes and browsers
• [x] No console errors or warnings
• [ ] User experience and accessibility have been tested
• [x] Added Storybook stories for new components
• [ ] Components follow design system guidelines (if applicable)

Screenshots (if applicable)

Attach screenshots here.