Generate specialized 'toString' for inline classes when possible

#KT-25613

compiler/testData/codegen/bytecodeText/inlineClasses/inlineClassInGeneratedToString.kt

@@ -0,0 +1,17 @@
+// !LANGUAGE: +InlineClasses
+
+// FILE: Z.kt
+inline class Z(val value: Int)
+
+// FILE: test.kt
+data class Data(val z1: Z, val z2: Z)
+
+inline class Inline(val z: Z)
+
+// @Data.class:
+// 0 Z.box
+// 0 Z.unbox
+
+// @Inline.class:
+// 0 Z.box
+// 0 Z.unbox

compiler/testData/codegen/bytecodeText/inlineClasses/inlineClassInStringTemplate.kt

@@ -0,0 +1,23 @@
+// !LANGUAGE: +InlineClasses
+
+// FILE: Z.kt
+inline class Z(val value: Int)
+
+// FILE: test.kt
+fun test1_1(z: Z) = "$z"
+fun test1_2(z: Z) = "$z$z"
+fun test1_many(z: Z) = "$z $z $z"
+fun test1_concat1(z: Z) = "-" + z
+fun test1_concat2(z: Z) = "$z" + z
+fun test1_concat3(z: Z) = "-" + z + z
+
+fun test2_1(z: Z?) = "$z"
+fun test2_2(z: Z?) = "$z$z"
+fun test2_many(z: Z?) = "$z $z $z"
+fun test2_concat1(z: Z?) = "-" + z
+fun test2_concat2(z: Z?) = "$z" + z
+fun test2_concat3(z: Z?) = "-" + z + z
+
+// @TestKt.class:
+// 0 box
+// 0 unbox

compiler/testData/codegen/bytecodeText/inlineClasses/resultApiDoesntUseBox.kt

@@ -34,4 +34,4 @@ fun test() {
 // 0 INVOKESTATIC Result.box-impl
 // 0 INVOKESTATIC Result.unbox-impl
 // 0 Result\$Failure
-// 53 Result
+// 52 Result