[BC Included] [DMN Designer] Data Types - Add popover for showing data types fields in the data types tab

Add popover for showing data types fields in the data types tab:

This JIRA comprehends:

• The new CSS for the data types name (rounded corner rectangle);
• The popover for the showing the new fields (with the link that redirects users to the source type);
• The removal of data types fields from data types with custom types (example: the "Employee (tPerson)" won't have fields anymore.