UUID support in search stream API endpoint

Is your feature request related to a problem? Please describe.
I am using Quickwit to ingest logs, and would like to make use of the ClickHouse integration to find associated data in ClickHouse. However, the join field is a UUID, which is currently being stored as a string in Quickwit. The stream endpoint is limited to returning int64 or uin64 values, which means there isn't a way for us to use this with UUIDs.

Describe the solution you'd like
It would be ideal if either:

• UUID was supported as a first class type in the index and allowed as a stream field, returned in ClickHouse native UUID format. (This is a binary format where the UUID is split into 2 uint64 values.)
• or if strings were allowed as a stream field

Describe alternatives you've considered
I can't see any alternatives, as storing the UUID as an integer would require 128-bit integer support. The current workaround I am using is to use a custom HTTP server to emulate the stream endpoint and do paged requests to the search endpoint, which is obviously far less performant than using the stream endpoint would be.

Start by tracing the search stream API endpoint and its current int64/uint64 field handling, then review how the ClickHouse integration consumes stream values. The work is complete when a supported UUID representation, or string stream fields, is agreed on and returned in a format usable by the ClickHouse join.