Add read/write instrumentation via OpenTelemetry

[reggiemcdonald]

Part of: #1392

Description

This PR adds read/write metrics to go-redis/redis. The following instruments were added:

• The number of reads
• The number of bytes written
• The number of bytes read
• Errors (read/write)

I embedded net.Conn into a tracedConn struct that enabled me to collect bytes written/read. Let me know what you think of this approach.

TODO

• There are general semantic conventions regarding attributes/labels. I would like to add the necessary labels to the metrics, but I would like to get approval of my general approach to collecting read/write bytes first, before adding the labels.

[reggiemcdonald]

/cc @nlehrer @danherr

[github-actions[bot]]

This pull request is marked stale. It will be closed in 30 days if it is not updated.