Resolve inconsistencies with standard asset search

**Describe the Feature**
The current search endpoint differs from the standard search endpoint at `api.aiod.eu` in multiple aspects. It would be nice to make it consistent at least in some of the aspects:

- [ ] Add pagination of results, i.e. add parameters `limit` and `offset`.
- [x] Rename query parameter `query` to `search_query`.
- [ ] Modify the response to contain only standard fields and change the `status` logic to use the status code instead.

**Considered Alternatives**
There is an option of implementing only some of the changes. Another alternative is to leave it as it is and let the other client services to rely on implementing the logic themselves.

**Additional context**
Motivation of this feature is to make it more consistent with the current search endpoint, e.g. `https://api.aiod.eu/search/datasets/v1`