[UX] Simplify/compact the bill creation UI for the common case

[asavageiv]

First off, thank you for your work on Cospend! It's amazing! I just have a bit of UX feedback.

The most common use case for me by far is adding a bill. The essentials are "What?" "How much?", "Who paid?" and "For whom?". I rarely to never touch "Payment mode", "Category", "Comment", "repeat", "Bill type", "Attach share link to person" or even "date". But all those extra options push "For whom?" below the fold on the narrow view so I have to scroll.

At a minimum, I'd like to rearrange the UI so in the narrow layout the "For whom?" appears after "Who paid?". Even better would be to put it after "For whom?" on all UIs because it's the natural follow up question to "Who paid?"

I'd also move the "Attach share link" to the bottom because it's not essential to bill creation. Or I'd just make it an icon to the left of the "What is this bill about" label.

Another option would be to hide the non-essential options behind an "Advanced" button.

Ideally these decisions would be usage stat driven, but I imagine that may be too much to ask here.