Code review dash: replace assignee emails with useravatarlink widget

[Ngoakor12]

Related issues: [code_review_dashboard: Make use of the user avatar element to link to people’s boards]

Description:

What are you up to? Fill us in :)

Screenshots/videos

I solemnly swear that:

• [x] My code follows the style guidelines of this project
• [x] I have merged the develop branch into my branch and fixed any merge conflicts
• [x] I have performed a self-review of my own code
• [ ] I have commented my code in hard-to-understand areas
• [x] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] New and existing unit tests pass locally with my changes

[Ngoakor12]

this task was resolved by #610