Support maximizing the commit preview in commit panel and diff area (staged/unstaged) in files panel.

Sometimes I am more interested in reading through the commit and see the code that is changed more than other areas. For that the commit patch panel breaks a lot of lines in side-by-side diff mode because there isn't a way to make it full screen.


**There are two ways to solve this**
1. In the `+`,`-` cycling through layouts. There can be a state in which after the commit browsing screen becomes full screen the next `+` makes the commit patches full screen. The same approach can be taken for the changed files panel.
2. Another more general approach is to allow collapse/hide the sidebar which will make the other panel almost full screen by default

**For alternative I am using the default git way like below**
`git diff shorthash^! `

**Additional context**
The above command gives me a diff screen like below. I would like something closer to this so that I can focus on the changes in the commit / changed files