Customizable line limit display on diff view

Problem to solve

With the current way the diff view is displayed, when you're working on projects that have a conventional line limit to be enforced (such as PHP PSR based projects), there is no way on the diff view to see whether lines go beyond that limit

Intended users

Developers / Reviewers

Proposal

Provide a customizable parameter to set the line limit length to be used in the diff view

(ex : for PSR based project it would be 120 characters per line)

Links / references

This issue relates to an older one : gitlab-foss#24626 (moved) But the actual feature has to go even further because not all projects use the same line limit.