Copy Java code style settings from briar core

When I was working on briar core code within IntelliJ while having the desktop project opened, I noticed that formatting would be messed up because it does not pick up the settings defined for briar core. I didn't find any better solution than just copying the Java and Javadoc settings from briar core to the desktop project. Since we don't have any Java code here, there is no conflict. Would be nice to be able to define this separately for subprojects or directories/source sets, but haven't found a way to do that. There are directory-based options you can put into .editorconfig files, but they seem to be a different type of formatter settings.