Reasons for creating this PR

Groups view in the sidebar does not currently have correct styling and sizing in Skosmos 3. This PR addresses that.

Link to relevant issue(s), if any

• Closes Groups view layout and styling #1727
• Part of Epic: Groups View Sidebar Tab #1704

Description of the changes in this PR

• Adds a new Font Awesome icon for all groups in group view
• Fixes sidebar width and height for groups view (+ width for other sidebar views)

Addresses requirements 3.1, 3.2, 3.4 in #1704

Known problems or uncertainties in this PR

Checklist

• phpUnit tests pass locally with my changes
• I have added tests that show that the new code works, or tests are not relevant for this PR (e.g. only HTML/CSS changes)
• The PR doesn't reduce accessibility of the front-end code (e.g. tab focus, scaling to different resolutions, use of .sr-only class, color contrast)
• The PR doesn't introduce unintended code changes (e.g. empty lines or useless reindentation)