metrics: add performance and application metrics for BTC staking

[SebastianElvis]

Fixes BM-1169

This PR introduces metrics for BTC staking. The metrics include both performance oriented ones and application specific ones. In particular, it includes

• performance: execution time of all relevant message handlers
• BTC staking module: number of finality providers and BTC delegations under each status, and total amount of staked Bitcoins
• finality module: last finalised height and last height (we can derive the gap of non finalised blocks by using them)

The implementation uses Cosmos SDK's native telemetry module.

[filippos47]

Thanks, these will be super handy!
Out of curiosity, how did you choose from which entity to emit the metrics? Afaik, Prom metrics are exposed both from the Telemetry module and a dedicated Prom server (by default listens to 26660).

[vitsalis]

This is very useful! Some questions about performance and types.

Also, let's change the base branch or wait until the new release before merging.

[SebastianElvis]

Afaik, Prom metrics are exposed both from the Telemetry module and a dedicated Prom server (by default listens to 26660).

I think all metrics specified using the telemetry package will be exposed by the prometheus server at :26660. The telemetry module gives all metrics specified by the developer to "github.com/hashicorp/go-metrics" (ref), more specifically to a singleton variable globalMetrics. When enabling metrics, the Metrics object will be created here, which imports metrics from "github.com/hashicorp/go-metrics". If you take a look at the code of Babylon and Cosmos SDK you might find that metrics specified by telemetry are presented in prometheus server.

[SebastianElvis]

Also, let's change the base branch or wait until the new release before merging.

Let's wait until the new release then. This PR will be affected by the new finality provider set rotation logic as well.

[SebastianElvis]

Thanks for the comments! This PR is now rebased to the latest dev and revised according to comments. Please feel free to take a look again.

[vitsalis]

Nice work!