Load execution ID from file

This MR introduces a new class IOHandler that encapsulates the most common I/O operations within the Theodolite framework. In order to do this, this MR also includes some restructuring/refactoring. With this handler, Theodolite uses a file expID.txt to store and load the execution ID for the next experiment.

theodolite-quarkus/src/test/kotlin/theodolite/util/IOHandlerTest.kt

@@ -79,7 +79,7 @@ internal class IOHandlerTest {
         )
     }
 
-    // Test the function `getResultFolderString
+    // Test the function `getResultFolderString`
 
     @Test
     @ClearEnvironmentVariable.ClearEnvironmentVariables(
@@ -90,6 +90,16 @@ internal class IOHandlerTest {
         assertEquals("",IOHandler().getResultFolderURL())
     }
 
+
+    @Test()
+    @SetEnvironmentVariable.SetEnvironmentVariables(
+        SetEnvironmentVariable(key = "RESULTS_FOLDER", value = "./src/test/resources"),
+        SetEnvironmentVariable(key = "CREATE_RESULTS_FOLDER", value = "false")
+    )
+    fun testGetResultFolderURL_FolderExist() {
+        assertEquals("./src/test/resources/", IOHandler().getResultFolderURL())
+    }
+
     @Test()
     @SetEnvironmentVariable.SetEnvironmentVariables(
         SetEnvironmentVariable(key = "RESULTS_FOLDER", value = "$FOLDER_URL-0"),