Handle coverage from instrumented binaries

[fmorency]

Go 1.20 added support for coverage profiling support for integration tests as described here. This feature enables one to generate a single coverage report containing unit, integration, and e2e test results.

The interchaintest project already supports creating complex containerized e2e test setups and run. However, there's currently no friendly way of retrieving the coverage data of those tests when using coverage-instrumented binaries.

I built a solution that works in liftedinit/manifest-ledger#45 but I believe a less "hacky" way would benefit the interchaintest project.

Let me know if this is something that can interest this community. I'm happy to discuss it!