Few fixes to Introduce Variable (no new features added)

Added few tests to Introduce Variable
More strict requirements for expressions to introduce it.

idea/testData/refactoring/introduceVariable/FewOccurrences.kt

@@ -0,0 +1,13 @@
+fun a() {
+    1
+    1
+    if (true) <selection>1</selection>
+}
+/*
+fun a() {
+    val i = 1
+    i
+    i
+    if (true) i
+}
+*/

idea/testData/refactoring/introduceVariable/It.kt

@@ -0,0 +1,16 @@
+fun a(op: (Int) -> Int) {}
+fun b() {
+    a {it}
+    a {
+        <selection>it</selection>
+    }
+}
+/*
+fun a(op: (Int) -> Int) {}
+fun b() {
+    a {it}
+    a {
+        val i = it
+    }
+}
+*/

idea/testData/refactoring/introduceVariable/LoopRange.kt

@@ -0,0 +1,9 @@
+fun a() {
+    for (a in <selection>1..2</selection>) {}
+}
+/*
+fun a() {
+    val intRange = 1..2
+    for (a in intRange) {}
+}
+*/

idea/testData/refactoring/introduceVariable/ManyInnerOccurences.kt

@@ -0,0 +1,25 @@
+fun a() {
+    if (true) {
+        if (true) {
+            1
+        }
+    } else {
+        if (true) {
+            <selection>1</selection>
+        }
+    }
+}
+/*
+fun a() {
+    val i = 1
+    if (true) {
+        if (true) {
+            i
+        }
+    } else {
+        if (true) {
+            i
+        }
+    }
+}
+*/

idea/testData/refactoring/introduceVariable/ManyOccurrences.kt

@@ -0,0 +1,33 @@
+fun a() {
+    if (true) {
+        <selection>1</selection>
+    }
+    if (true) {
+        1
+    }
+    if (true) {
+        1
+    } else {
+        if (true) {
+            1
+        }
+    }
+}
+/*
+fun a() {
+    val i = 1
+    if (true) {
+        i
+    }
+    if (true) {
+        i
+    }
+    if (true) {
+        i
+    } else {
+        if (true) {
+            i
+        }
+    }
+}
+*/

idea/testData/refactoring/introduceVariable/ReplaceOccurence.kt

@@ -0,0 +1,11 @@
+fun a(x: Int) {}
+fun b() {
+    a(<selection>1</selection>)
+}
+/*
+fun a(x: Int) {}
+fun b() {
+    val i = 1
+    a(i)
+}
+*/

idea/testData/refactoring/introduceVariable/SimpleCreateValue.kt

@@ -0,0 +1,8 @@
+fun a() {
+    <selection>1</selection>
+}
+/*
+fun a() {
+    val i = 1
+}
+*/

idea/testData/refactoring/introduceVariable/StringInjection.kt

@@ -0,0 +1,9 @@
+fun a() {
+    "it's a number ${<selection>1</selection>}"
+}
+/*
+fun a() {
+    val i = 1
+    "it's a number ${i}"
+}
+*/

idea/testData/refactoring/introduceVariable/WhenParts.kt

@@ -0,0 +1,15 @@
+fun a() {
+    when (1) {
+        is 3 -> 1
+        is 4 -> <selection>1</selection>
+    }
+}
+/*
+fun a() {
+    val i = 1
+    when (i) {
+        is 3 -> i
+        is 4 -> i
+    }
+}
+*/

idea/testData/refactoring/introduceVariable/WhileCondition.kt

@@ -0,0 +1,9 @@
+fun a() {
+    while (<selection>true</selection>) {}
+}
+/*
+fun a() {
+    val b = true
+    while (b) {}
+}
+*/