KT-5079 Support smart completion for when values

#KT-5079 Fixed

idea/testData/completion/smart/WhenEntryValue1.kt

@@ -0,0 +1,16 @@
+enum class E {
+    A
+    B
+    C
+}
+
+fun foo(e: E) {
+    when(e) {
+        <caret>
+    }
+}
+
+// EXIST: E.A
+// EXIST: E.B
+// EXIST: E.C
+// EXIST: {"lookupString":"else","tailText":" ->","itemText":"else"}

idea/testData/completion/smart/WhenEntryValue2.kt

@@ -0,0 +1,16 @@
+enum class E {
+    A
+    B
+    C
+}
+
+fun foo(e: E) {
+    when(e) {
+        E.A, <caret>
+    }
+}
+
+// ABSENT: E.A
+// EXIST: E.B
+// EXIST: E.C
+// ABSENT:else

idea/testData/completion/smart/WhenEntryValue3.kt

@@ -0,0 +1,17 @@
+enum class E {
+  A
+  B
+  C
+}
+
+fun foo(e: E) {
+    when(e) {
+        E.A -> x()
+        <caret>
+    }
+}
+
+// ABSENT: E.A
+// EXIST: E.B
+// EXIST: E.C
+// EXIST: {"lookupString":"else","tailText":" ->","itemText":"else"}

idea/testData/completion/smart/WhenEntryValue4.kt

@@ -0,0 +1,17 @@
+enum class E {
+    A
+    B
+    C
+}
+
+fun foo(e: E) {
+    when(e) {
+        <caret>
+        else -> x()
+    }
+}
+
+// EXIST: E.A
+// EXIST: E.B
+// EXIST: E.C
+// ABSENT: else

idea/testData/completion/smart/WhenEntryValue5.kt

@@ -0,0 +1,17 @@
+enum class E {
+    A
+    B
+    C
+}
+
+fun foo(e: E) {
+    when(e) {
+        E.A -> x()
+        E.<caret>
+    }
+}
+
+// ABSENT: A
+// EXIST: B
+// EXIST: C
+// ABSENT: else

idea/testData/completion/smart/WhenEntryValue6.kt

@@ -0,0 +1,18 @@
+enum class E {
+  A
+  B
+  C
+}
+
+fun foo(e: E?) {
+    when(e) {
+        E.A -> x()
+        <caret>
+    }
+}
+
+// ABSENT: E.A
+// EXIST: E.B
+// EXIST: E.C
+// EXIST: null
+// EXIST: {"lookupString":"else","tailText":" ->","itemText":"else"}

idea/testData/completion/smart/WhenEntryValue7.kt

@@ -0,0 +1,15 @@
+enum class E {
+  A
+  B
+  C
+}
+
+fun foo(e: E) {
+    when(e) {
+        <caret>
+        E.B -> x()
+    }
+}
+
+// EXIST: E.A
+// ABSENT: else

idea/testData/completion/smart/WhenEntryValue8.kt

@@ -0,0 +1,11 @@
+import java.lang.annotation.ElementType
+
+fun foo(e: ElementType) {
+    when(e) {
+        ElementType.FIELD -> x()
+        <caret>
+    }
+}
+
+// ABSENT: ElementType.FIELD
+// EXIST: ElementType.TYPE

idea/testData/completion/smart/WhenWithNoSubjectEntryValue1.kt

@@ -0,0 +1,11 @@
+fun foo(b1: Boolean, b2: Boolean) {
+    when {
+        <caret>
+    }
+}
+
+// EXIST: b1
+// EXIST: b2
+// ABSENT: true
+// ABSENT: false
+// EXIST: {"lookupString":"else","tailText":" ->","itemText":"else"}

idea/testData/completion/smart/WhenWithNoSubjectEntryValue2.kt

@@ -0,0 +1,8 @@
+fun foo(s: String) {
+    when {
+        s.<caret>
+    }
+}
+
+// EXIST: equals
+// ABSENT: else