It's difficult to read Merge Request differences when you are red/green colorblind

Description

I'm a color blind user and it's difficult to read Merge Request diffs inside of a merge request in the red and green colors chose. I've played with the other themes, but they all have a similar green and red color.

Proposal

It would be nice to change it to something like blue/yellow rather than red/green.

Overview

What is it? Add an area in settings / themes where an addition and subtraction color can be set

Why should someone use this feature? Anyone that is red/green color blind would use this feature

What is the underlying (business) problem? I'm unable to read the diff structure at a glance

How do you use this feature? I use it multiple times a day to monitor changes to our code base

Use cases

Who is this for? Provide one or more use cases. Anyone that is color blind.

Feature checklist

Make sure these are completed before closing the issue, with a link to the relevant commit.