Add Coverage Reports

[kuzdogan]

More and more we are uncovering issues that could've been prevented if we had coverage reports.

We should start generating coverage reports of the code and increase the code coverage.

The newly added packages should have a built-in coverage report tool with the boilerplate, we can utilize that.

What we need:

• Code coverage report for all code: server, monitor, lib-sourcify, bytecode-utils, contract-call-decoder etc.
  • Shows which lines are covered
• A the report embedded in the respective repos. We can use codecov. They have a free open-source tier.
  • Example: ethereumjs repo https://github.com/ethereumjs/ethereumjs-monorepo

_{View in Huly HI-371}

[marcocastignoli]

• lib-sourcify coverage: 1f4759d