SwapBinaryExpression: implementation cleaned up, tests renamed

#KT-4868 Fixed

idea/testData/intentions/swapBinaryExpression/assignment.kt

@@ -0,0 +1,5 @@
+// IS_APPLICABLE: false
+fun main() {
+    var mutablevar = 20
+    mutablevar = <caret>10
+}

idea/testData/intentions/swapBinaryExpression/equals.kt

@@ -1,5 +1,3 @@
-// IS_APPLICABLE: false
-fun main() {
-    var mutablevar = 20
-    mutablevar = <caret>10
+fun neq(a: Int, b: Int) {
+    if (a ==<caret> b) {}
 }

idea/testData/intentions/swapBinaryExpression/identityEquals.kt

@@ -0,0 +1,3 @@
+fun neq(a: Int, b: Int) {
+    if (a ===<caret> b) {}
+}

idea/testData/intentions/swapBinaryExpression/identityEquals.kt.after

@@ -1,3 +1,3 @@
 fun neq(a: Int, b: Int) {
-    if (a ==<caret> b) {}
+    if (b === a) {}
 }

idea/testData/intentions/swapBinaryExpression/identityEqualsLiteral.kt

@@ -0,0 +1,3 @@
+fun neq(a: Int, b: Int) {
+    if (a identityEquals<caret> b) {}
+}

idea/testData/intentions/swapBinaryExpression/identityEqualsLiteral.kt.after

@@ -0,0 +1,3 @@
+fun neq(a: Int, b: Int) {
+    if (b identityEquals a) {}
+}

idea/testData/intentions/swapBinaryExpression/notIDentityEquals.kt.after

@@ -0,0 +1,3 @@
+fun neq(a: Int, b: Int) {
+    if (<caret>b !== a) {}
+}

idea/testData/intentions/swapBinaryExpression/notIdentityEquals.kt

@@ -1,4 +1,3 @@
-// IS_APPLICABLE: false
 fun neq(a: Int, b: Int) {
     if (<caret>a !== b) {}
 }

idea/testData/intentions/swapBinaryExpression/plusMinus.kt

@@ -0,0 +1,3 @@
+fun test(): Int {
+    return 1 <caret>+ 2 - 3
+}

idea/testData/intentions/swapBinaryExpression/plusMinus.kt.after

@@ -0,0 +1,3 @@
+fun test(): Int {
+    return 2 + 1 - 3
+}