Extraction Engine: Generate function/property accessor with expression body (whenever applicable)

#KT-6405 Fixed

idea/testData/refactoring/extractFunction/controlFlow/evaluateExpression/evalIfExpr.kt.after

@@ -8,6 +8,4 @@ fun foo(a: Int): Int {
     return i(a, b) 
 }
 
-private fun i(a: Int, b: Int): Int {
-    return if (a + b > 0) 1 else if (a - b < 0) 2 else b
-}
+private fun i(a: Int, b: Int) = if (a + b > 0) 1 else if (a - b < 0) 2 else b