Run Evalscript button should be disabled if there were no changes to script

[janybravo]

Problem:
CodeEditor component already seems to do nothing when refresh button is clicked consequently with no script modifications. But user could get an impression that there were some changes that needs to be applied.

Solution:
So having button disabled would improve UX a bit.

Context
Refresh eval script button would be disabled on EOBrowser on already applied script content.