First part was to "reverse" MavenCli into CLIng, that also became a huge and complex beast. Now, sanitization comes, tearing down unneeded stuff. CLIng should be simple and straightforward.

Now the invoker fully parses args, creates Maven instance (ie. local, using Maven components on classpath) and invokes Maven. The new executor in turn does NOT fully parses args and is logical equivalent of maven-invoker.

Changes:

• radically simplify CLIng existing classes (and especially API - the fact we have "local", "resident" etc invoker is actually implementation detail).
• introduce "executor", a "lower level" tool that does not parse args (and is logical equivalent of maven-invoker) and support Maven 4.x and Maven 3.x.