Files in dockerfile don't have executable

[gx1]

Describe the bug
When the file are saved in dockerfile panel, set chmod +x if the user set the executable flag
This is a problem because when the container is built, you could require to have executable files.

To Reproduce
Steps to reproduce the behavior:

1. Go to dockerfiles directory
2. Drag a file
3. Select the file
4. Save and build
5. Run the container
   The script cannot be used for permission denied issues .

Expected behavior
It should be possible to set permission in front-end.