Fix missing intubation dates

[skeating]

Description

In some cases people appear not to have a placement date for a tube although we know we are receiving ventilator data so they must have had a tube inserted

Definition of Done

• We record placement date as being the date we first receive ventilator data

Dependencies

Comments

[MonikaSvata]

The relevant information of intubation placement date and extraction are not correct. @skeating will implement solution to get intubation duration.

[MonikaSvata]

Missing intubation dates to be let empty and let the users to investigate or assume and fill in.
This should be included in the documentation.