CV Helptexts

Implements SEN-174

Goal of this MR:

• adds help icons to the values of the CV dropdowns when the definition property of the CV entities are filled
• adds an help icon for the selected value of a CV dropdown when the definition property of the CV entity is filled
• currently implemented for Compartment, Sampling Media, Measured Quantity, Unit and Resolution Unit (but so far visible only for Measured Quantity)