Migrate HAML project avatars to `Pajamas::AvatarComponent`

What does this MR do and why?

Related to #345020 (closed)

Migrate project avatars using project_icon helper to Pajamas::AvatarComponent. This also adds support for retina screens because Pajamas::AvatarComponent adds the srcset attribute behind the scenes.

Screenshots or screen recordings

Taken on a retina screen. Notice that the Intrinsic size is at 2x.

Project front page

Before	After

Project breadcrumbs

Before	After

Group -> Settings -> Projects

Before	After

Create project from user instance template

Before	After

Create project from group template

Before	After

How to set up and validate locally

On a retina screen...

Project front page and project breadcrumbs

1. Upload an avatar to a project and visit the home page

Group -> Settings -> Projects

1. Go to a project in a group and upload an avatar
2. Go to the parent group -> Settings -> Projects

Create project from user instance template

1. Follow instructions in https://docs.gitlab.com/ee/administration/custom_project_templates.html
2. Go to /projects/new#create_from_template and choose the Instance tab

Create project from group template

1. Follow instructions in https://docs.gitlab.com/ee/user/group/custom_project_templates.html
2. Go to /projects/new#create_from_template and choose the Group tab

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.