Frontend gives no control over query provider selection and should not assume query provider

[Enet4]

The frontend is currently assuming "lucene" as the query provider. This does not work in Dicoogle installations using a different index for DICOM content. Instead, the application should look up the list of query providers installed, and allow the user to select those providing DIM-level results.

Note that it is already possible to do searches without indicating a preference for query provider, so removing all places where "lucene" is hardcoded already improves the user experience in most cases.

[luis-godinho]

Hi, i have removes the hardcoded instances of lucene, here is the PR for that change PR.