A full reorganization of the networking logic

While we're at it, make the packet files mostly Checkstyle clean, except for Javadocs (not very useful)

build-logic/src/main/kotlin/velocity-checkstyle.gradle.kts

@@ -7,4 +7,6 @@ extensions.configure<CheckstyleExtension> {
     maxErrors = 0
     maxWarnings = 0
     toolVersion = libs.checkstyle.get().version.toString()
+    configProperties["org.checkstyle.google.suppressionfilter.config"] =
+            rootProject.file("config/checkstyle/checkstyle-suppressions.xml")
 }