Add features added in a story map to the bottom by default

Challenge

When adding features in a story map, you usually add them top-to-bottom. if you later visit the feature board, the features will be in the opposite order -- the most recently added at the top, instead of the bottom. This feels very confusing, especially if you use order as priority.

Desired UX

When adding features to a story map, they should be added to the bottom by default. It would be even nicer if we could add them in the same order as the map (adding in between two features should stay in between those two features), but that seems less important.