win_stat: Add stat.isreg support (#27732)

* win_stat: Add stat.isreg support

This PR includes the following changes:
- Adds stat.isreg support (cfr. the stat module)
- Always returns stat.isdir, stat.islnk, stat.isreg, stat.isshared

* Remove the controversial part

lib/ansible/modules/windows/win_stat.py

@@ -173,6 +173,11 @@ stat:
             returned: success, path exists
             type: boolean
             sample: True
+        isreg:
+            description: if the path is a regular file
+            returned: success, path exists
+            type: boolean
+            sample: True
         isshared:
             description: if the path is shared or not
             returned: success, path exists