Define basic repo workflows

[phbnf]

• Submit configs for

  • dependabot
  • codeql: it's not in the trillian-tessera repo, but it's in the c-t-go repo, let's add it here as well and see how it goes
  • go_test
  • golanci-lint
  • govulncheck

• Edit the repo config such that it requires these workflows to pass:

  • go_test
  • golanci-lint: we don't have this requirement in trillian-tessera, but I think it should be fine to have it? I'll try!
  • govulncheck

Scorecard is enabled in c-t-go, not in trillian-tessera. I'm not enabling it here either since this is still under heavy development. We'll add this later.

[roger2hk]

I don't have access to add golangci-lint into the required tests. It should be required.

[phbnf]

Note that I might update a few things later on when we have integration tests, but that should be good enough to start!