[query] Allow retrieving raw/unadjusted traces

[yurishkuro]

For debugging purposes it is often useful to look at the original JSON of the trace as it is stored in the database. This can be done by supporting an extra parameter in the trace API /api/traces/{traceID}/?raw=true.

Caveat: there trace is still going to go through a series of transformation: dbmodel -> domain model -> ui/JSON model, but those transformations are more or less lossless.