[ansiconsole] provide API to check if ANSI is enabled

When executing a program (e.g. maven, cucumber,...) one usually want to enable a "monocrome" mode if ansi is disabled.

There currently is `org.eclipse.ui.internal.console.ansi.preferences.AnsiConsolePreferenceUtils.isAnsiConsoleEnabled()` but this is private and not accessible to programs.

It would therefore be good to have a way to check if ansi is enabled in general and of course for a console instance @mihnita I think we once already discussed this and decided to "do it sometime later" but it seems it havent happened yet.