Alert Management|Details page: update some styles and attributes

What does this MR do?

1. Introduces the alert badge to the top of the page
2. Moves severity to the overview list
3. Re-formatts the overview list, as displayed (so that it's no longer all left-aligned - the titles are right-aligned, and the values are left-aligned)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines

#216084 (closed)