added themed alias table shading

[danoswaltCL]

• Adds shading to visually highlight site + target groupings on alias table on overview page and stepper page.
• Uses $theme to make sure this works for both light and dark themes.
• Set up to be reusable for other tables if we want shading used elsewhere.
• Refactors duplicate implementations of a alias-table-creation method into one common service method

[jreddig]

its beautiful. and its in the stepper and experiment detail!