Update package name across the project (#2)

* Change package name

* Update publication

* Update docs

* Update settings.gradle.kts, README and CONTRIBUTING

* Cleanup leftovers

samples/kotlin-mcp-server/src/main/kotlin/Main.kt

@@ -91,7 +91,7 @@ fun configureServer(): Server {
 
     // Add a tool
     server.addTool(
-        name = "Test org.jetbrains.kotlinx.mcp.Tool",
+        name = "Test io.modelcontextprotocol.kotlin.sdk.Tool",
         description = "A test tool",
         inputSchema = Tool.Input()
     ) { request ->