Add option to show whitespace characters in diff

**Is your feature request related to a problem? Please describe.**
It would be nice to be able to see whitespace characters in the diff panel. Sometimes I see stuff like this:


My IDE displays the whitespace characters like this:


**Describe the solution you'd like**
An option to enable displaying whitespace characters.

**Describe alternatives you've considered**
Maybe highlighting the parts of the line that changed could help.