Refine kotlin code (#1241)

* style(kotlin): Improve kotlin codes readability.

* remove redundant quotes.

* style(kotlin): improve codes readability.

* style(kotlin): refine kotlin codes.

* Create kotlin.yml

* Create kotlin.yml

* Delete .github/workflows/kotlin

* Delete .github/workflows/main.yml

* Create kotlin.yml

* Update kotlin.yml

* Delete .github/workflows/kotlin.yml

* Create hello_world_workflow.main.kts

* Delete .github/workflows/hello_world_workflow.main.kts

* remove empty line

codes/kotlin/utils/Vertex.kt

@@ -19,8 +19,8 @@ class Vertex(val value: Int) {
         }
 
         /* 输入顶点列表 vets ，返回值列表 vals */
-        fun vetsToVals(vets: List<Vertex?>): List<Int> {
-            val vals = ArrayList<Int>()
+        fun vetsToVals(vets: MutableList<Vertex?>): MutableList<Int> {
+            val vals = mutableListOf<Int>()
             for (vet in vets) {
                 vals.add(vet!!.value)
             }