Bring in a JLine-based console in a modular way

[gbrail]

The "tools" module has a bunch of code that tries to use reflection to load a nice console using JLine when it's in the classpath.

Now that our codebase is modular, do this in a nicer way by creating a new top-level "rhino-cli" module for this. Include this module in "rhino-all" so that the default experience has a nice CLI.

Update the various "tools" programs to load the JLine console if it is available, and if it is not, or not on an interactive terminal, fall back to the old-fashioned console based on System.in and System.out.

This does add JLine as a dependency in "rhino-all." If this is an issue for users, we could "shade" it using a plugin, or we could just suggest that folks who don't want a full-fledged CLI use the new modules instead of "rhino-all" and not include the new CLI module if they don't want it.

This doesn't carry forward the old completer code that we used to have -- I didn't find that to work reliably with the current JLine. There's room for future improvement there.

[gbrail]

This might be helpful to some of you, it certainly improves the experience for me, I'd love it if a few people could try it out.

[aardvark179]

This looks pretty good—though we will need to ensure we don't pull in JLine on our fork. You might want to tweak the default run cradle task a little because it run the REPL without JLine.

[ZZZank]

Not sure if old behaviour is good behaviour, but I think it is possible to avoid changing it, by doing something like this:

private final Optional<Terminal> terminal; // type in generic param so that at runtime JVM will load `Optional.class` instead of `Terminal.class`

public JLineConsoleProvider() {
    try {
        terminal = Optiona.of(...);
    } catch (Throwable t) {
        // capture `Throwable`, including `NoClassDefFoundError` when JLine is not present
        terminal = Optional.empty();
    }
}

And by doing so we can merge rhino-cli into rhino-tools because JLine can be compileOnly dependency

(please ignore the fact that I targeted this comment at line 34 for no reason)