jg-swirlds

### Problem Java 8 still has a large amount of market share (roughly 50% right now), and from appearances the need for more recent versions of Java in the Hedera...

This issue covers the following tasks: 1. Add SpotBugs to the build process, generating HTML report 2. Socialise the HTML report with relevant team members 3. Drive the reported issue...

Introducing a CODEOWNERS file to auto-assign PR reviews, as detailed here: https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-code-owners

Most of the links in the root readme were 404'ing. This PR fixes them.