Create a component to show the severity of the merge request violation

Problem to solve

Merge request violations can have different severities #299356 (closed), we need to display this in a way that conveys the severity visually.

Proposal

Create a table cell to display the severities: High, Medium, Low, Info.

Implementation

frontend weight 1️⃣

1. Create a table cell component to display the MR violation severity.
   • See if we can reuse app/assets/javascripts/sidebar/components/severity/severity.vue
2. Update specs