feat(Border Radius): Fixing Atoms' border radii

[LinKCoding]

Overview

Addressing the atoms first, fixing border radii
See notion for more details: https://www.notion.so/codecademy/Border-Radius-Tracker-55c1c9e9ab49480995d314ac3fb784ff

PR Checklist

• Related to designs:
• Related to a mixture of JIRA tickets: GM-592, GM-892, GM-828, GM-830
• I have run this code to verify it works
• This PR includes unit tests for the code change
• This PR includes testing instructions tests for the code change
• The alpha package of this PR is passing end-to-end tests in all relevant Codecademy repositories

Testing Instructions

1. Visit the notion page to see a list of changed components, go to their relative paths and check that things render the same and work the same way.

[dreamwasp]

left some code-only review comments, gonna test locally in a bit