* chore: add test for ensuring pipeline previews work for trace parser processors
* chore: updates to trace parser validation in postable pipelines
* chore: extract auth.randomHex into utils.RandomHex for reuse
* chore: get trace parser preview test passing
* chore: start with JSON serialized trace parser in test to cover deserialization
* chore: address PR feedback
* chore: add test for previewing pipeline with grok parser
* chore: import grok parser in logparsing preview to ensure its a registered logtransform op
* chore: add dependencies for grok parsing operator
* chore: rename model.GetLogsResponse -> model.SignozLog for use in both requests and responses
* feat: add test for simulating log pipelines processing
* feat: get pipeline preview tests passing
* chore: cleanup
