Add method to include other project as included build

^KT-45745 In Progress

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/testbase/testDsl.kt

@@ -257,6 +257,23 @@ class TestProject(
             """.trimIndent()
         )
     }
+
+    fun includeOtherProjectAsIncludedBuild(
+        otherProjectName: String,
+        pathPrefix: String
+    ) {
+        val otherProjectPath = "$pathPrefix/$otherProjectName".testProjectPath
+        otherProjectPath.copyRecursively(projectPath.resolve(otherProjectName))
+
+        projectPath.resolve(otherProjectName).addDefaultBuildFiles()
+
+        settingsGradle.append(
+            """
+            
+            includeBuild '$otherProjectName'
+            """.trimIndent()
+        )
+    }
 }
 
 private fun commonBuildSetup(