CAL-891	[Add Calendar] "Select Group" isn't localized

Fix description:
- i18n "Select Group" word in tab Show in Groups.
- i18n select group label in UICalendarForm class.
- use key UICalendarForm.label.AddGroupInput for Select Group label
- add variable to get "Select Group" translation
Merge commit '25a8e31b90e305d2a7da5306424782d15f128ffa' into HEAD