Merge branch '5-set-up-firebase' into 'main'

android/AndroidManifest.xml

android/build.gradle

android/src/com/wordbattle/game/AndroidInterfaceClass.java

android/src/com/wordbattle/game/AndroidLauncher.java

build.gradle

core/src/com/wordbattle/game/WordBattle.java

core/src/com/wordbattle/game/network/FirebaseInterface.java

core/src/com/wordbattle/game/network/FirebaseManager.java

desktop/src/com/wordbattle/game/DesktopInterfaceClass.java

desktop/src/com/wordbattle/game/DesktopLauncher.java

gradle.properties