Expandable transports view

This branch makes the transports view in the nav drawer expandable.

The view is collapsed by default. Clicking anywhere in the view expands it, and scrolls the nav drawer if necessary to make the expanded view visible. Clicking on the expanded view's chevron collapses it.

Compared to the status quo this has the slight advantage of showing the "Connections" label by default, which gives some context to the other controls. The toggles are hidden unless the user expands the view. This could be good (visual simplicity) or bad (harder to discover the toggles).