Add a role that can be used to create local links (a la '`LINK`_'), but
that also applies literal style. This is particularly useful for
referring to subcommands within the command's documentation in a style
that is consistent with ':command:`BAR <foo(BAR)>`' but is much less
verbose.

Although this is intended for subcommands, it works with any local
reference.

Co-authored-by: Brad King <brad.king@kitware.com>