feat: update default font

[andrey-canon]

Description

This replaces the DIN Next LT Arabic font with IBM Plex Sans Arabic.

How to test

1. Set the learning(this version) MFE as a volume
2. Add the module.config.js file into the frontend-app-learning folder and restart your container

module.exports = {
    localModules: [
        { moduleName: '@edx/brand', dir: '../brand-openedx'},
    ],
};

3. Checkout this branch and verify

Before

After