Remaining inconsistencies of the color field

[lukasbestle]

I have retested the state of develop-minor after #6152 with the HTML examples in the XSS lab, specifically the test cases I wrote down in the issue here: #6056 (comment)

The new implementation unfortunately still suffers from HTML rendering issues:

• All examples except the "Color (query, defaults)" example seem to double-escape the label. So we can render the label as HTML in Vue.
• The "Color (query, defaults)" example does not seem to double-escape, which means that the default query does not escape on the backend. If I remember correctly with the other options fields, the query mode needs to escape on the backend so that the frontend can safely render as HTML.

To reproduce:

• Pull the latest commits of the Sandbox
• (Re)Load the Lab environment
• Go to the XSS page and look at the 8 color fields
  • Everything labeled "This is OK" should be rendered as HTML and displayed in green
  • The "API (with HTML)" field should also render the bold part in the label
  • No red "Malicious string" should be rendered in red