Introduce "Unused unary operator" inspection

#KT-12073 Fixed

idea/testData/inspectionsLocal/unusedUnaryOperator/.inspection

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.inspections.UnusedUnaryOperatorInspection

idea/testData/inspectionsLocal/unusedUnaryOperator/basic.kt

@@ -0,0 +1,6 @@
+// "Remove unused unary operator" "true"
+fun test(foo: Int?): Int {
+    val a = 1 + 2
+    <caret>+ 3
+    return a
+}

idea/testData/inspectionsLocal/unusedUnaryOperator/basic.kt.after

@@ -0,0 +1,6 @@
+// "Remove unused unary operator" "true"
+fun test(foo: Int?): Int {
+    val a = 1 + 2
+    3
+    return a
+}

idea/testData/inspectionsLocal/unusedUnaryOperator/basic2.kt

@@ -0,0 +1,6 @@
+// "Remove unused unary operator" "true"
+fun test(foo: Int?): Int {
+    val a = 1 + 2
+    <caret>- 3
+    return a
+}

idea/testData/inspectionsLocal/unusedUnaryOperator/basic2.kt.after

@@ -0,0 +1,6 @@
+// "Remove unused unary operator" "true"
+fun test(foo: Int?): Int {
+    val a = 1 + 2
+    3
+    return a
+}

idea/testData/inspectionsLocal/unusedUnaryOperator/usedAsExpression.kt

@@ -0,0 +1,6 @@
+// PROBLEM: none
+fun test(foo: Int?): Int {
+    val a = (1 + 2
+            <caret>- 3)
+    return a
+}

idea/testData/inspectionsLocal/unusedUnaryOperator/usedAsExpression2.kt

@@ -0,0 +1,4 @@
+// PROBLEM: none
+fun test(foo: Int?): Int {
+    return <caret>-1
+}

idea/testData/inspectionsLocal/unusedUnaryOperator/userOperator.kt

@@ -0,0 +1,11 @@
+// PROBLEM: none
+data class Point(val x: Int)
+
+operator fun Point.plus(other: Point) = Point(this.x + other.x)
+
+operator fun Point.unaryMinus() = Point(-x)
+
+fun test() {
+    val p = Point(1) + Point(2)
+    <caret>-Point(3)
+}