Add Colors to GitLab Flavored Markdown

What does this MR do?

Adds color codes support to GFM.

Codes which are written in form `color` will be followed by a color "chip".

Are there points in the code the reviewer needs to double check?

• According to the hierarchy of pipelines, ColorFilter is added to BroadcastMessagePipeline, SingleLinePipeline.
• Should ColorFilter be supported by EmailPipeline?
• There is a collision with an issue number typing(see screenshots). RESOLVED

Why was this MR needed?

This was a feature request. It is more comfortable to discuss colors when you can see their visual representations.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
  • Has been reviewed by Backend
  • Has been reviewed by Database
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together
• Internationalization required/considered

What are the relevant issue numbers?

Resolves #24167 (closed)