Better explanation and clearer errors on code indexing

[kevinvandijk]

In #1704 it becomes clear that many people don't know that qdrant needs to run for code indexing to work. Starting this discussion to see how we can improve the UI for this .

[adamhill]

Just a simple GET for the endpoint give you info that it is up. This works locally and remotely as is.

>> curl http://localhost:6333/ \
     -H "api-key: <apiKey>"
>> {"title":"qdrant - vector search engine","version":"1.15.1","commit":"af7ab5b192f01c9d9cd7fff119eab2ae73755cc0"}%

MVP - a "Test Qdrant Connection" button that gets a green check icon if it is working. Maybe auto ping on Kilo activation.
Refinement - Warning indicator over / on / color change the Indexing Badge in the Chat UI and in the Indexing setitings.
Both will need aria- announcemnts & description changes for a11y following the example of the changes for PR#<indexing_a11y_number_here>