feat: add marketplace

[jxhnx]

TODO:

// solution 1 // discarded

• (a) Cypher query buildOfferInfoQuery should properly reflect Gaia-X schema relationships used in the marketplace, no wildcards
• (b) Offerings with multiple resources are not linked at the moment (e.g., data resource not linked to its respective service access point); linkage should come from the result of the cypher query in (a)
• (c) Relationship (b) should properly be reflected in the UI in one carousel

// solution 2

• Refactor, so that display in UI is dynamically build over Offer id, where each linked relation is a new query; or find solution to get a "sub-graph", which keeps the relations intact without transformations into other objects. Solution 1 tries to combine everything in one query, put that into a custom object -- while trying to keep graph relations in a non-graph-format -- and rebuild the information from there.