Implement Unwrap/Remove for conditionals and loops

idea/testData/codeInsight/unwrapAndRemove/unwrapThen/thenCompoundInBlock.kt

@@ -0,0 +1,12 @@
+// OPTION: 1
+fun foo(n: Int): Int {
+    <caret>if (n > 0) {
+        println("> 0")
+        n + 10
+    } else {
+        println("<= 0")
+        n - 10
+    }
+
+    return n
+}

idea/testData/codeInsight/unwrapAndRemove/unwrapThen/thenCompoundInBlock.kt.after

@@ -0,0 +1,7 @@
+// OPTION: 1
+fun foo(n: Int): Int {
+    <caret>println("> 0")
+    n + 10
+
+    return n
+}

idea/testData/codeInsight/unwrapAndRemove/unwrapThen/thenCompoundInReturn.kt

@@ -0,0 +1,10 @@
+// IS_APPLICABLE: false
+fun foo(n: Int): Int {
+    return <caret>if (n > 0) {
+        println("> 0")
+        n + 10
+    } else {
+        println("<= 0")
+        n - 10
+    }
+}

idea/testData/codeInsight/unwrapAndRemove/unwrapThen/thenSimpleInReturn.kt

@@ -0,0 +1,8 @@
+// OPTION: 0
+fun foo(n: Int): Int {
+    return <caret>if (n > 0) {
+        n + 10
+    } else {
+        n - 10
+    }
+}

idea/testData/codeInsight/unwrapAndRemove/unwrapThen/thenSimpleInReturn.kt.after

@@ -0,0 +1,4 @@
+// OPTION: 0
+fun foo(n: Int): Int {
+    return <caret>n + 10
+}