Do not display architect's birth(death)day if unknown

[normade]

If an architects birthday is unknown, but the year is known, do not display the random date.

Context: In the backend it is marked with a flag if only the year is known and a random date is given in the field which is wrong. It should not be displayed. The flag needs to be considered until the backend comes up with a better solution and/or reworks the endpoints in a certain way.

We could discuss how to solve that backend-side and implement it then for both mobile apps.

Relates to:
Modernism-in-Architecture/modernism#158
Modernism-in-Architecture/MIA-flutter#36

Example:
Jaeger's day of death is unknown but it does display 1.1.1993. Only 1993 is a fact. (The birthday is by luck correct the 1st Jan).