Icon for MATLAB .m files in repository tree is not appropriate

Summary

MATLAB source files with .m extension appear in the repository tree with a "letter C" icon that is also used for .c files written in C. These icons seem to be a relatively recent addition via !28112 (merged). This is despite the feature that displays the composition of languages used in a repository successfully recognising the presence of lots of MATLAB code and no C code when this is the true composition of the repository.

Steps to reproduce

1. Add a .m file written using MATLAB syntax to a repository
2. Browse to a list of repository files where the added file is visible.

Example Project

See for example the project root for https://gitlab.com/tensors/tensor_toolbox (the most-starred MATLAB project on GitLab.com) which contains several .m files.

What is the current bug behavior?

The icon used is a "C"

What is the expected correct behavior?

A MATLAB-specific icon, M-related icon or generic file icon should be used.

Information for implementation:

• File icons map: https://gitlab.com/gitlab-org/gitlab-svgs/-/blob/main/src/file_icon_map.js#L123
• https://github.com/material-extensions/vscode-material-icon-theme/blob/main/images/fileIcons.png