Refactor catalogue browsing to work with a mock response

[xamcost]

Hi there! The goal of this issue is to remove the example catalogue we've been using in our app so far to replace it with a mock response closer to what is expected from the Sedimark local catalogue component. As mentioned in this post, this mock response should be a simple json array such as:

[
  {"title": "Lung cancer 2019", "short_description": "This dataset...", "provider": "Atos", "price": 2.5, "created": "2022:11:15T23:54:00", "keywords": [...]},
  {"title": "Billionaire 2023", "short_description": "This dataset...", "provider": "Surrey", "price": 3.5, "created": "2022:12:01T23:54:00", "keywords": [...]},
 ...
]

It should contain only the information needed in the cards representing the results in the catalogue browsing page. It should not be influenced by other offering data that may appear in the offering contracting page (#9 ) or in the offering management dashboard (#11 and #12 ): these will be mocked directly or separately.

As a final note, we should keep in mind that the list of providers appearing in the filters of the catalogue browsing page is not built from this mock response. We assume that a separate request will be made to fetch it, so it should be mocked separately.