Introduce separate callee expression for when with subject variable

'Subject.Error' is redundant.
'Subject.None' can be an object.
'Subject#dataFlowValue' can be a lateinit property.

TODO: fix
- parsing local extension properties in 'when' subject
- parsing destructuring declarations in 'when' subject
- non-completed calls in nested 'when' with subject variable
- non-completed calls for subject variable in 'in' pattern

compiler/tests-common/tests/org/jetbrains/kotlin/checkers/AbstractDiagnosticsTest.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.checkers
 import com.intellij.openapi.util.io.FileUtil
 import com.intellij.openapi.util.text.StringUtil
 import com.intellij.psi.search.GlobalSearchScope
+import junit.framework.TestCase
 import org.jetbrains.kotlin.analyzer.AnalysisResult
 import org.jetbrains.kotlin.analyzer.common.CommonAnalyzerFacade
 import org.jetbrains.kotlin.cli.jvm.compiler.NoScopeRecordCliBindingTrace
@@ -53,6 +54,7 @@ import org.jetbrains.kotlin.test.util.DescriptorValidator
 import org.jetbrains.kotlin.test.util.RecursiveDescriptorComparator
 import org.jetbrains.kotlin.test.util.RecursiveDescriptorComparator.RECURSIVE
 import org.jetbrains.kotlin.test.util.RecursiveDescriptorComparator.RECURSIVE_ALL
+import org.jetbrains.kotlin.utils.addToStdlib.cast
 import org.jetbrains.kotlin.utils.keysToMap
 import org.junit.Assert
 import java.io.File