added scheme and kotlin to code_search

crates/g3-core/examples/test_code/Example.kt

@@ -0,0 +1,24 @@
+package com.example
+
+class Person(val name: String, val age: Int) {
+    fun greet() {
+        println("Hello, I'm $name")
+    }
+    
+    fun getAge(): Int {
+        return age
+    }
+}
+
+interface Greeter {
+    fun sayHello()
+}
+
+fun main() {
+    val person = Person("Alice", 30)
+    person.greet()
+}
+
+fun add(a: Int, b: Int): Int {
+    return a + b
+}