Search: Icon to be defined for each Space Type

[me-andre]

Description

Historically, on Search page each journey type had its own icon (Space, Challenge, Opportunity). With switch to [sub]spaces and intro of extra space types such as KNOWLEDGE and BLANK_SLATE, we don't have icons for them anymore. As a quick fix I did a fallback to the most generic SpaceIcon, but we may want to either:

1. remove those space types from search
2. introduce new space icons

Acceptance criteria

• [ ] Should ‹testable condition that should be satisfied›
• [ ] …

Additional Context

Relevant file: src/domain/shared/components/JourneyIcon/JourneyIcon.tsx

Areas that will be affected

To be added during the refinement