✨ add a nu-check verification CI (#771)

I made a `toolkit.nu` with a very bare bones struct, this is called via
[`setup-nu`](https://github.com/hustcer/setup-nu) action, and generates
the `check-files.nu` file. After that, another nu instance run that
script to check files one by one. The folder `before_v0.60/` is
excluded.

toolkit.nu

@@ -0,0 +1,64 @@
+# this module regroups a bunch of development tools to make the development
+# process easier for anyone.
+#
+# the main purpose of `toolkit` is to offer an easy to use interface for the
+# developer during a PR cycle.
+
+
+# check that all the tests pass
+export def test [
+] {
+    print "toolkit test: not implemented!"
+}
+
+# run all the necessary checks and tests to submit a perfect PR
+export def "check pr" [
+] {
+    generate-file-list
+    test
+}
+
+export def main [] { help toolkit }
+
+export def generate-file-list [ --full ] {
+    let start = "let files = ["
+
+    mut files = [""]
+
+    if $full {
+        # all the *.nu files in the repo
+        # exept for `before_v0.60`
+        print "checking all files..."
+        mut $files = glob **/*.nu --exclude [before_v0.60/**]
+    } else {
+        # only the *.nu files changed in comparison with origin/main
+        $files = (git diff --name-only origin/main | lines | filter { str ends-with '.nu'} | each { path expand })
+    }
+
+
+    let new_list = $files | str join ",\n" | append "]"
+
+    let final = "
+
+    mut exit_code = 0
+    for file in $files {
+        let diagnostics_table = nu --ide-check 10 $file | to text | ['[', $in, ']'] | str join | from json
+        let result = $diagnostics_table | where type == \"diagnostic\" | is-empty
+        if $result {
+            print $\"✔ ($file) is ok\"
+        } else {
+            print $\"❌ ($file) has errors:\"
+            print ($diagnostics_table | where type == \"diagnostic\" | reject span)
+            $exit_code = 1
+        }
+    }
+    print $\"💚 All files checked!\"
+
+exit $exit_code
+"
+
+    $start 
+    | append $new_list
+    | append $final 
+    | save "check-files.nu" --force
+}