remove `check-nushell-files` (!204)

this removes the `check-nushell-files.nu` script i left in !200.

scripts/check-nushell-files.nu

-let files = ^git lf | lines | where { ($in | path parse).extension == "nu" }
-
-for f in $files {
-    let path = $env.FILE_PWD | path dirname | path join $f
-
-    try {
-        nu-check $path --debug
-    } catch { |e|
-        let err = $e.debug
-            | ansi strip
-            | parse --regex '(.*)msg: "Found : (?<msg>.*)", span: (?<span>.*)'
-            | into record
-
-        error make --unspanned {
-            msg: ([
-                $"(ansi red_bold)($e.msg)(ansi reset):",
-                $"    file: (ansi purple)($f)(ansi reset)",
-                $"    err:  ($err.msg)",
-            ] | str join "\n")
-        }
-    }
-}