Odd empty state layout

[bertob]

The empty state is a bit odd visually, I think primarily because

• The hierarchy is unclear, there isn't a single thing to focus on first, or path for the eye to move
• The layout is very different from other apps do
• The switch with two labels with different text styling feels off
• The disabled back/forward buttons are superfluous

A few tips for a better layout:

• Drop subtitle in the headerbar and make it a statuspage header instead
• Add a statuspage icon (probably the app icon or symbolic)
• Add a description explaining the
• Make the file picker a suggested pill button
• Drop the text styling on the Lossy/Lossless labels
• Drop the back/forward buttons

[Huluti]

@akozlovskiy119 have made good suggestion also in #66

[Huluti]

Most of suggestions taken in #138 and next steps in #139