refactor: replace metrics-rs with opentelemetry-rust

[yangby-cryptape]

Purpose

• Remove all tokio<1.0 dependencies.

  Reduce 502 - 483 = 19 dependencies.

• Fix the metrics feature, it was broken since v0.43.0.

Changes

• (BREAK CHANGES) Due to the refactor of metrics-rs >0.12.1, we couldn't keep the same configurations as before.

  Since the metrics feature is an experimental and development-only feature, I just made some break changes.

• According to the suggestion from @doitian, replaces metrics-rs with opentelemetry-rust.

  As opentelemetry-rust said, it is not stable, too, so I didn't change the APIs. I just wrote a series of compatible macros.

  Due to the difference of those two crates, the presentation of data couldn't be totally the same as before.

  We could tweak them later according to actual requirements.

In the Further

I just let it works again, it only supports export data over a Prometheus endpoint with a preset settings, now.

Any more changes should be added later, according to actual requirements.

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This change is 

[doitian]

Reviewed 8 of 8 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @quake)

[yangby-cryptape]

bors merge=doitian,driftluo

[bors]

Build succeeded:

• ci