build(model-api-gen): removed the gradle functionalTest

There is a separate project "model-api-gen-gradle-test" that does the
same test. The gradle functionalTest is hard to debug, because all the
generated files are deleted at the end of the test run. That's why this
separate test project was added.

Author: slisson

model-api-gen-gradle/build.gradle.kts

@@ -31,3 +31,14 @@ gradlePlugin {
         implementationClass = "org.modelix.metamodel.gradle.MetaModelGradlePlugin"
     }
 }
+
+val writeVersionFile by tasks.registering {
+    val propertiesFile = projectDir.resolve("src/main/resources/modelix.core.version.properties")
+    propertiesFile.parentFile.mkdirs()
+    propertiesFile.writeText("""
+        modelix.core.version=$version
+    """.trimIndent())
+}
+tasks.named("processResources") {
+    dependsOn(writeVersionFile)
+}