version: add system platform to versions report

Some platforms, such as Darwin, do not postitively identify the platform
name in any of the other system fields currently in the versions report.

Improves #21906.

salt/version.py

@@ -608,6 +608,7 @@ def system_information():
             return ' '.join(win_ver)
 
     system = [
+        ('platform', platform.system()),
         ('dist', ' '.join(platform.dist())),
         ('release', platform.release()),
         ('machine', platform.machine()),