Introduce a tasks feature

Since we can create checklist items in docs and on a canvas it would be useful if they were all collected into one location. That way we can view and edit them from one location.

Compared to dedicated task manager apps where we are forced to create to-dos in a vertical list we can create them in a more natural environment on a surface where creating them are part of our workflow. So naturally it would be useful if Whimsical could then collect them all into a Tasks feature.