Add toggle control for chapter/verse selector

The UI for selecting a limited verse range wasn't the best, since those
fields went unused most of the time. Added a toggle control for the
selector so users can ignore it when it isn't needed. Also adapted E2E
test for the project page to expect the new UI element.
Prevent chapter and verse from being zero

In a previous commit, we prevented the chapter and verse numbers in the
range selector from being negative -- but zero doesn't make any sense
either. Leaving them blank already means "from the start/end of the
passage/chapter" respectively, so there's no need to also allow zeroes.
So instead, the minimum for each control will be 1.
Edit existing text: if user cancels, uncheck box

If the user clicks "Cancel" on the "This is dangerous" popup, or on the
"You have unsaved edits that will be lost if you proceed" popup, then we
should return the "Edit existing text" checkbox to the false state, to
avoid any user confusion about whether the UI has listened to his
request to cancel the operation.