Add: SignatureService

Improve requested room validation by using newly added SignatureService

build.gradle

@@ -30,6 +30,7 @@ dependencies {
     // Fabric API. This is technically optional, but you probably want it anyway.
     modImplementation "net.fabricmc.fabric-api:fabric-api:${project.fabric_version}"
     shadow('com.maxmind.geoip2:geoip2:4.2.0')
+    implementation("io.javalin:javalin:6.4.0")
     shadow('com.google.inject:guice:7.0.0') {
         exclude group: 'com.google.guava', module: 'guava'
         exclude group: 'com.google.guava', module: 'listenablefuture'