Expand AddMaxWeight to Ferries

[paulklie]

Currently the AddMaxWeight Quest only asks the maxweight of bridges and around 0.79% of bridges have such a max weight tagged.

Expanding this to ferries (route=ferry) seems rather easy. I would suggest keeping the other limitations on access and motor_vehicle, since we dont want to ask about pedestrian only ferries: https://github.com/streetcomplete/StreetComplete/blob/6eaf52d3eb7027b8d292f907b2b0b02366120523/app/src/main/java/de/westnordost/streetcomplete/quests/max_weight/AddMaxWeight.kt#L26

Currently around 0.79% of bridges have a max weight tag, while 0.787% of ferries have a max weight tag. While around 1.4% of bridges are maxweight:signed=no and no ferries have this tag. This leads me to believe that ferries are more likely to have their maxweight signed, which also matches my experience in my area.