Display alt text for the avatar

What does this MR do and why?

Adds the alt property to the avatar in the Breadcrumb

Screenshots or screen recordings

How to set up and validate locally

Adding an avatar to Group

1. Go to /admin/groups
2. Pick a group that has a project
3. Add an avatar to the group. A small PNG will do. Adding JPEG did not work for me.

Validating

1. Go to the project that belongs to the group
2. Click on Repository
3. Inspect the avatar on the group level breadcrumb item

It should display the Group name as the alt property.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #368708 (closed)