Make MatchOptions::new const

[kangalio]

Little quality of life change that would allow you to create static glob configurations for use throughout the program, like this

pub const CASE_INSENSITIVE_GLOB: glob::MatchOptions = glob::MatchOptions {
    case_sensitive: false,
    ..glob::MatchOptions::new()
};

glob::glob_with("...", CASE_INSENSITIVE_GLOB)

Of course you can easily work around this by manually specifying all the fields. It would be convenient to be able to fill in default values, though :)

[KodrAus]

This sounds good to me! We currently test this crate against 1.23.0, but that release is very old, so I'd be ok with bumping it to support const fn.