feat(su): implement metrics in the su

[VinceJuliano]

Background

The MU and CU now have metrics capabilities implemented, however because the SU is in Rust it has not been implemented there yet.

Solution

find a Rust version of the metrics library used in the MU and CU and implement it in the SU. Or find any Rust library that outputs the same metrics format and implement that. Make sure metrics can be turned on and off via an environment variable.

[VinceJuliano]

There is a prometheus client for Rust

https://docs.rs/prometheus-client/latest/prometheus_client/

Here are some useful metrics

• A Histogram that measures the runtime of message retrieval on the query endpoint
• A Histogram that measures the runtime of the get_messages function
• A Counter on each http endpoint
• A Counter on DataItems that have failed to upload
• A Histogram that measures the runtime of the write_item function
• A Histogram that measures the time it takes to acquire the lock in write_item