Add favicons

...rc/main/java/ch/epfl/autograde/config/SecurityConfig.java

...sources/static/images/favicons/android-chrome-192x192.png

...sources/static/images/favicons/android-chrome-512x512.png

...ain/resources/static/images/favicons/apple-touch-icon.png

...src/main/resources/static/images/favicons/favicon-120.png

...src/main/resources/static/images/favicons/favicon-128.png

...src/main/resources/static/images/favicons/favicon-152.png

.../src/main/resources/static/images/favicons/favicon-16.png

...src/main/resources/static/images/favicons/favicon-180.png

...src/main/resources/static/images/favicons/favicon-228.png

.../src/main/resources/static/images/favicons/favicon-32.png

.../src/main/resources/static/images/favicons/favicon-57.png

.../src/main/resources/static/images/favicons/favicon-76.png

.../src/main/resources/static/images/favicons/favicon-96.png

...ice/src/main/resources/static/images/favicons/favicon.ico

...grade-service/src/main/resources/templates/error/4xx.html

...grade-service/src/main/resources/templates/error/5xx.html