[Feature]: GraphQL search query

### Contact Details

_No response_

### What should we build?

A GraphQL resolver 'search' with parameters: entity, query (free-text search), filter (structured search)

Plug it into the same code as used by the `/api/search/` endpoints.

Deprecate `subscriptions` resolver. 
Deprecate all other methods of searching.




### Relevant pseudo code

```shell

```