"Eliminate argument of 'when'": do not suggest if 'when' is used as expression and it has no 'else' branch (#2898)

#KT-35526 Fixed

idea/testData/intentions/branched/when/eliminateSubject/withoutElse.kt

@@ -0,0 +1,11 @@
+enum class Type {
+    HYDRO,
+    PYRO
+}
+
+fun select(t: Type) {
+    <caret>when (t) {
+        Type.HYDRO -> 1
+        Type.PYRO -> 42
+    }
+}

idea/testData/intentions/branched/when/eliminateSubject/withoutElse.kt.after

@@ -0,0 +1,11 @@
+enum class Type {
+    HYDRO,
+    PYRO
+}
+
+fun select(t: Type) {
+    when {
+        t == Type.HYDRO -> 1
+        t == Type.PYRO -> 42
+    }
+}

idea/testData/intentions/branched/when/eliminateSubject/withoutElseUsedAsExpression.kt

@@ -0,0 +1,12 @@
+// IS_APPLICABLE: false
+enum class Type {
+    HYDRO,
+    PYRO
+}
+
+fun select(t: Type): Int {
+    return <caret>when (t) {
+        Type.HYDRO -> 1
+        Type.PYRO -> 42
+    }
+}