Add empty state inside pipeline editor section

What does this MR do?

Adds an empty state to the pipeline editor section. Instead of showing an error message, we show a nice pretty SVG. A follow=up will be made this milestone to add a CTA to the section to start writing your ci config in the Pipeline Editor directly.

Screenshots (strongly suggested)

Before	After

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides

Availability and Testing

Added unit tests, no need for additional coverage.