JPS tests: restore MPP tests runner, support new MPP model

build-common/test/org/jetbrains/kotlin/incremental/testingUtils/incrementalModificationUtils.kt

@@ -67,12 +67,18 @@ fun getModificationsToPerform(
             val underscore = fileName.indexOf("_")
 
             if (underscore != -1) {
-                val module = fileName.substring(0, underscore)
+                var moduleName = fileName.substring(0, underscore)
+                var moduleFileName = fileName.substring(underscore + 1)
+                if (moduleName.all { it.isDigit() }) {
+                    val (moduleName1, moduleFileName1) = moduleFileName.split("_")
+                    moduleName = moduleName1
+                    moduleFileName = moduleFileName1
+                }
 
                 assert(moduleNames != null) { "File name has module prefix, but multi-module environment is absent" }
-                assert(module in moduleNames!!) { "Module not found for file with prefix: $fileName" }
+                assert(moduleName in moduleNames!!) { "Module not found for file with prefix: $fileName" }
 
-                return Pair(module, fileName.substring(underscore + 1))
+                return Pair(moduleName, moduleFileName)
             }
 
             assert(moduleNames == null) { "Test is multi-module, but file has no module prefix: $fileName" }