Rakefiles should be processed as Ruby scripts

Summary

Icons of Rakefiles shown in file lists should be Ruby icons in merge request change lists.

Steps to reproduce

Make changes in a Rakefile and display the related file header in a change list (under 'Changes' tab when displaying a merge request).

Example Project

Find any merge request which include Rakefile changes.

What is the current bug behavior?

The icon displayed is the icon used for standard files.

What is the expected correct behavior?

The icon displayed should be the icon used for every Ruby script since a Rakefile is a specialized Ruby script.

Relevant logs and/or screenshots

Output of checks

Possible fixes

By default, assuming Rakefile filenames are Ruby files.