Added more formats for PS

[tempergate]

-extended file formats for PS
-added nushell file format to language regex
-extended language name in a list of languages

[nightroman]

@tempergate Any explanation why this is needed, what this nushell is?

-extended language name in a list of languages

I think changing the description of the scheme in the list is redundant, even if we agree with the extra extension.

[nightroman]

Grok says

Nushell does not use PowerShell as its programming language or scripting language.

And here is its example script. It does not look like PowerShell at all.

#!/usr/bin/env nu

# hello.nu
def main [name: string = "world"] {
    print $"Hello ($name | str capitalize)!"
}

# Optional subcommands
def main greet [who: string] {
    print $"Greetings, ($who)!"
}

[nightroman]

@ctapmex I suggest closing this PR. Apart from main issues, it seemingly includes a few irrelevant commits.