More testing, lower coupling, better docs

• Fix some small quirks like print messages
• Change report summary so it now prints to stdout instead of stderr
• Decouple config from the input scanner (now uses the trait)
• Remove a dependency on MockAll
• Move some dependencies to a specific dev-dependencies profile
• Reorganize integration/regression/system tests in a dedicated tests folder.
• Adds system tests in Rust, invoking the binary in a similar way to the Bash script but it is much more flexibility and powerful than the Bash script. There's still a bunch more tests that could be added this way.
• Adds large amount of unit tests