[observability] http tracing

[BohuTANG]

Summary

Add REST API to rpc/http for showing logs from the web side.

Reference:
tokio-rs/tracing#884
https://github.com/tokio-rs/console
https://github.com/tokio-rs/tracing/tree/master/tracing-opentelemetry

[BohuTANG]

This task is easy after #879, the REST API can read tracing from system.tracing:
SELECT * FROM system.tracing

[jyz0309]

/assignme

[jyz0309]

/help

[databend-bot]

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[jyz0309]

I think this issue needs more discussion, for example: What is the format of Json? What content should be kept in the system.tracing table to be shown in the api.

[BohuTANG]

ok, thank you @jyz0309
The initial design we can make it work and next to choose the pretty format, how about your thoughts?

[jyz0309]

ok, thank you @jyz0309
The initial design we can make it work and next to choose the pretty format, how about your thoughts?

I think you are right. Maybe we can just show the logs in the initial design (v0.5). And in the 0.6 version, we can just format it in the Json.