Add benchmarks for go-header

Result of discussion with @Wondertan

The goal is to add benchmarks for various scenarios and testing for block time and size limits.

Option 1:
- Expand go-header metrics coverage in go-header
- Pull metrics into Granfana board
- Multiple implementations can use the same Grafana board

Option 2:
- Write the Knuu test that spins up the network and desired topology
- Call API needed to be measured like (produce and retrieve blocks or headers)
- Measure the time between calls
- Optionally make some reusable benchmarking tooling for Knuu

Start by comparing the two proposed approaches: expanding go-header metrics with a Grafana board, or using a Knuu network and topology to measure block and header APIs. Identify the relevant APIs and scenarios for block time and size limits, then define which benchmarks and tests demonstrate completion.

Written by the indexing model from the issue text.