Add new severity symbols to Sketch

Background:

From this issue: gitlab#34352 (closed) we are redesigning our severity badges to be more clear, quickly identifiable, scaleable, and accessible.

New badge designs:

Old badge	New badge	New badge color
		#8B2615
		#C0341D
		#FCA429
		#FDBC60
		#418CD8
		#919191

Specs:

• Icon size: 12px x 12px
• Padding between icon and Label: 8px
• Label text: Default Paragraph

Checklist

Make sure these are completed before closing the issue, with a link to the relevant commit or issue, if applicable. Get familiar with the Sketch UI Kit documentation which has information on updating files, structure, fonts, and symbols.

1. Author: Create a Sketch file in your progress folder with the changes required for this issue. Try to use existing symbols, layer styles, and text styles.
2. Author: Ask another Product Designer to review your personal Sketch file, linking them to your latest commit so they know where to find it. If they have the capacity, they should assign themselves to this issue. If not, try pinging another person.
3. Reviewer: Review and approve author's changes in their personal Sketch file, according to the workflow.
4. Author: Add your changes to the GitLab Sketch UI Kit (pattern library and/or instance sheet), following this step-by-step process.
5. Author: Ask the reviewer to review your changes to the Sketch UI Kit files.
6. Reviewer: Review and approve author's changes to the Sketch UI Kit files, according to the workflow.
7. Author: Create an issue in the Design System to update the design specs and documentation. Mark it as related to this issue.
8. Author: Add a read only (FYI) agenda item to the next UX weekly call to inform everyone of these changes, linking to this issue.