Description of the problem: In order to be visually consistent with other buttons that are side by side in RHDH, we should add a space between the "Back" and "Next" buttons in the workflow execution screen:

In the software template creation screen, the buttons have a space:

and in the workflow instance screen:

In addition, the disabled "Back" button should be grey to match the other disabled buttons' color.
How reproducible: 100%

Steps to reproduce:

1. Deploy orchestrator 1.3 rc4 with latest rc3 plugins

2. Execute greeting workflow.

Actual results: See above

Expected results: Buttons should be visually consistent.