Short description (with a reference to an issue).
This PR adds users an opportunity to add label(s) about the calendar_range input fields, as for now it is quite complicated to add labels above start and end calendars fields precisely.

calendar_range(          input_id = "calendar_range",          start_value = "2020-02-20",          end_value = "2020-03-20",          min = "2020-01-01",          max = "2020-12-01",          start_placeholder = "Select range start",          end_placeholder = "Select range end",          start_label = "Start Date",          end_label = "End Date"        )

In general, to existingcalendar_range function added two argumentsstart_label andend_label
The example app showcasing has been also completed.examples/calendar_range

DoD

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