Simplify data binding

The raw editor's model is now managed by a getter setter that takes
care of handling the raw model, which must be sanitized. (There may
still be room for refactoring here -- could setter leverage
`makeLightblueRequest`?). This means that the rest of the form inputs
can use much more straightforward binding. Inputs that aren't valid to
form a request, but aren't invalid from a UX or application point of
view, can get pruned from the request before execution.