SSDM-11657 : NG UI : fix warnings that appear in development mode - fixed problems shown in a browser debug console

SSDM-11372 : script editor in new admin UI not very responsive - make script editor scrollable in X axis to prevent line wrapping which in some cases may give an impression of frozen editor (e.g. when a tab is added in a wrapped line)

NG_UI : plugins : SSDM-10401 - make the source code editor look and behave more like to other form fields

NG_UI : layout : clean up theme provider - introduce separate constants for background and border colors