Update svgo tools

Purpose

Just small clean up:

• Update svgo to 2.8.0 which contains lots of fixes and improvements to further make our SVGs smaller.
• Drop svg4everybody as we don't support IE11 anymore.
• Update svg-sprite to 2.0.0

Screenshots

Checklist

For a new icon and/or illustration:

• Link to related design issue:
• If this adds an icon ensure that it follows the new icon checklists.
• If this adds an illustration ensure that it follows the new illustration checklists.

For third-party trademarks:

• If this adds or updates an icon or illustration that includes a third-party trademark, ensure that it follows the process for adding third-party trademarks to GitLab.