[FIR] Introduce a feature flag for context-sensitive enum resolution

The feature was previously enabled unconditionally in K2 which
triggered a bug when an enum has an entry with the same name as itself.

#KT-58897 Fixed
#KT-52774

compiler/fir/analysis-tests/testData/resolve/unqualifiedEnum/correctJava.kt

@@ -1,3 +1,4 @@
+// LANGUAGE: +ContextSensitiveEnumResolutionInWhen
 // FILE: JavaEnum.java
 
 public enum JavaEnum {

compiler/fir/analysis-tests/testData/resolve/unqualifiedEnum/incorrectJava.kt

@@ -1,3 +1,4 @@
+// LANGUAGE: +ContextSensitiveEnumResolutionInWhen
 // FILE: JavaEnum.java
 
 public enum JavaEnum {

compiler/fir/analysis-tests/testData/resolve/unqualifiedEnum/nested.kt

@@ -1,3 +1,4 @@
+// LANGUAGE: +ContextSensitiveEnumResolutionInWhen
 enum class Outer {
     FIRST, SECOND;
 }

compiler/fir/analysis-tests/testData/resolve/unqualifiedEnum/notInsideBranches.kt

@@ -1,3 +1,4 @@
+// LANGUAGE: +ContextSensitiveEnumResolutionInWhen
 enum class Some {
     FIRST,
     SECOND;

compiler/fir/analysis-tests/testData/resolve/unqualifiedEnum/priority.kt

@@ -1,3 +1,4 @@
+// LANGUAGE: +ContextSensitiveEnumResolutionInWhen
 // FILE: first.kt
 
 package first

compiler/fir/analysis-tests/testData/resolve/unqualifiedEnum/typeAlias.kt

@@ -1,3 +1,4 @@
+// LANGUAGE: +ContextSensitiveEnumResolutionInWhen
 enum class Some {
     FIRST,
     SECOND;

compiler/fir/analysis-tests/testData/resolve/unqualifiedEnum/unqualifiedEnum.kt

@@ -1,3 +1,4 @@
+// LANGUAGE: +ContextSensitiveEnumResolutionInWhen
 package test
 
 enum class Sample {