McMaster.Extensions.CommandLineUtils 2.3.0

## Enhancements: * Support the POSIX convention for cluster multiple options. For example, `-ixd` is treated the same as `-i -x -d`. * @bjorg: support SingleOrNoValue notation. `--option[:value]` * New type: `Pager`. Provides a simple interaction model for displaying console output in a pager. * Display help text using the `less` pager on macOS/Linux. * Make suggestions when invalid options or commands are used, but there is a valid one that is similar. (Thanks to @MadbHatter for doing the initial work on this.) * Add support for subcommand aliases. Commands can be given multiple names. * Obsolete the constructor of `[Subcommand]` which takes a string. * Infer subcommand names from the type name * @lvermeulen: Sort subcommands by name in help text. This can be disabled with `DefaultHelpTextGenerator.SortCommandsByName`. * @jcaillon: Add API for `UnrecognizedCommandParsingException` which includes suggestions for similar options or commands. * @TheConstructor: add CommandLineApplication.GetValidationResult() ## Bugs fixed: * Duplicate subcommand names used to cause undefined behavior. Now, attempting to add a duplicate subcommand name or aliases will cause the library to throw before the app can execute. * Fix bug in subcommand name inference. When not specified, the subcommand always matched the entry assembly name. In this update, this convention only applies to the parent command. * Add generic overloads of `.IsRequired()` for `CommandOption<T>` and `CommandArgument<T>`. * @handcraftedsource: handled nested HelpOptions (fixes #86 - InvalidOperationException when multiple help options were defined) See more details here: https://github.com/natemcmaster/CommandLineUtils/blob/master/CHANGELOG.md#v230