Create sidenav with DG Menu and Course Key section

src/app/degree-planner/degree-planner.component.html

src/app/degree-planner/degree-planner.component.scss

...lanner/sidenav-menu-item/sidenav-menu-item.component.html

...lanner/sidenav-menu-item/sidenav-menu-item.component.scss

...ner/sidenav-menu-item/sidenav-menu-item.component.spec.ts

...-planner/sidenav-menu-item/sidenav-menu-item.component.ts

src/app/shared/shared.module.ts

src/assets/material-theme.scss

src/assets/sass/general.scss