Fix bogus smartcast on enum entry members

Previously, enum entries were treated by the data-flow subsystem similar
to other class/singletons. As a consequence, calls like
'Enum.ENTRY.property' had IdentifierInfo of 'property'.

However, specially for enum entries, descriptor of 'property' is one and
the same for all entries. It means that from the data-flow point of
view, 'Enum.ONE.property' and 'Enum.TWO.property' are *one and the same
data-flow values*.

It could obviously lead to some bogus smartcasts, so this commit
introduces separate IdentifierInfo.EnumEntry and uses it to build proper
qualified values.

^KT-20772 Fixed

compiler/tests/org/jetbrains/kotlin/checkers/DiagnosticsTestGenerated.java

@@ -18849,6 +18849,16 @@ public class DiagnosticsTestGenerated extends AbstractDiagnosticsTest {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/elvisRHS.kt");
             }
 
+            @TestMetadata("enumEntryMembers_after.kt")
+            public void testEnumEntryMembers_after() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_after.kt");
+            }
+
+            @TestMetadata("enumEntryMembers_before.kt")
+            public void testEnumEntryMembers_before() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_before.kt");
+            }
+
             @TestMetadata("equals.kt")
             public void testEquals() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/equals.kt");

compiler/tests/org/jetbrains/kotlin/checkers/javac/DiagnosticsUsingJavacTestGenerated.java

@@ -18849,6 +18849,16 @@ public class DiagnosticsUsingJavacTestGenerated extends AbstractDiagnosticsUsing
                 runTest("compiler/testData/diagnostics/tests/smartCasts/elvisRHS.kt");
             }
 
+            @TestMetadata("enumEntryMembers_after.kt")
+            public void testEnumEntryMembers_after() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_after.kt");
+            }
+
+            @TestMetadata("enumEntryMembers_before.kt")
+            public void testEnumEntryMembers_before() throws Exception {
+                runTest("compiler/testData/diagnostics/tests/smartCasts/enumEntryMembers_before.kt");
+            }
+
             @TestMetadata("equals.kt")
             public void testEquals() throws Exception {
                 runTest("compiler/testData/diagnostics/tests/smartCasts/equals.kt");