Update avatar component to have more flexibility around text styles

Description

The labeled avatar component only allows the user's name to be displayed in a bold text style. However, there are several instances in the product where a user avatar is designed without a bold name.

Avatar in MR assignees/reviewers	Avatar in issue assignees

These instances are not using the GLAvatar component, and while I am not sure of the exact reason, my assumption is that it has to do with the flexibility of text styles of the GLAvatar component.

We should allow more flexibility of text styles (weight and color) for the user's name in the avatar component.

Additional context: https://gitlab.slack.com/archives/CH9QG9TAQ/p1688675827145269

Checklist

Make sure the following are completed before closing the issue:

1. Assign the correct component label to this issue.
2. Create an MR with the additions or updates needed.
3. When applicable, create an issue using the Figma update issue template to update the component in Figma, and mark it as related to this one. Bring the issue to your team planning session for prioritization and scheduling.
4. When applicable, create an MR in GitLab UI to update the component. If you do not have capacity or are unable to update the component directly, create a GitLab UI issue using the Component issue template. Mark the new issue as related to this one. Bring the issue to your team planning session for prioritization and scheduling. Mark the issue as related to this one.
5. When introducing a major or breaking change, communicate the changes within the Engineering Week in Review and UX Weekly meeting.
6. 🎉 Congrats, you made it! You can now close this issue.