Update Icons Documentation about Icon Vue Component

What does this MR do?

It adds documentation about our new icon vue component.

Why was this MR needed?

So we have documentation on \doc\development\fe_guide\icons.md

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Review
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #38451 (closed)