Improve diff view mode

[Mingun]

Is your feature request related to a problem? Please describe. Currently diff view occupies only central pane of the application. Usually you don't need to know which branches you have when you examine diffs. So I suggest to expand diff view to the left.

Also, there a frequently used options that should have quick switches:

• enable/disable word wrapping
• enable/disable whitespace ignore mode
• it would also useful if editor will show whitespaces, but quick switch for that is not required

Describe the solution you'd like Make changes as shown on the screenshot

Describe alternatives you've considered None

Additional context

[JetpackDuba]

Please split it in multiple issues, one per change. I may work on them separately so it's easier to keep track of the progress.

[Mingun]

Ok, left this for expanding diff view. The two new issues is for settings is linked above this message

[JetpackDuba]

Thank you 😁