added prebuild step for core modules to resolve build issues

* generating several core modules before the main languages build helps
to resolve weird compiler issues with JavacTool compiler that came up after
2021.1 migration

Author: wsafonov

build.gradle

@@ -219,7 +219,12 @@ task buildAllScripts(type: BuildLanguages, dependsOn: [resolveMps, resolveDepend
     script "$buildDir/scripts/build-allScripts.xml"
 }
 
-task buildLanguages(type: BuildLanguages, dependsOn: buildAllScripts) {
+task prebuild(type: BuildLanguages, dependsOn: buildAllScripts) {
+    script "$buildDir/scripts/prebuild.xml"
+    targets "clean", "generate"
+}
+
+task buildLanguages(type: BuildLanguages, dependsOn: prebuild) {
     script "$buildDir/scripts/build-languages.xml"
 }