KT-27524 Don't box (some) inline classes in suspend fun return

If an inline class is mapped to a reference type (or an array), it's Ok
to treat JVM view on a suspend function as returning a value of
corresponding inline class (although in reality it returns 'Any?'
because of COROUTINE_SUSPENDED).

compiler/testData/codegen/bytecodeText/coroutines/inlineClasses/inlineClassBoxingInSuspendFunReturn_Primitive.kt

@@ -0,0 +1,20 @@
+// IGNORE_BACKEND: JVM_IR
+
+inline class ICInt(val x: Int) // unbox-impl in generated 'equals'
+
+suspend fun suspendICInt(): ICInt = ICInt(1) // box-impl
+suspend fun suspendAny(): Any = ICInt(1) // box-impl
+suspend fun <T> suspendGeneric(x: T): T = x
+
+fun useICInt(x: ICInt) {}
+fun useAny(x: Any) {}
+
+suspend fun test() {
+    useICInt(suspendICInt()) // unbox-impl
+    useICInt(suspendGeneric(ICInt(1))) // box-impl, unbox-impl
+    useAny(suspendAny())
+    useAny(suspendICInt())
+}
+
+// 3 INVOKESTATIC ICInt\.box-impl
+// 3 INVOKEVIRTUAL ICInt\.unbox-impl

compiler/testData/codegen/bytecodeText/coroutines/inlineClasses/noInlineClassBoxingInSuspendFunReturn_Any.kt

@@ -0,0 +1,26 @@
+// IGNORE_BACKEND: JVM_IR
+
+inline class ICAny(val x: Any)
+
+suspend fun suspendICAny(): ICAny = ICAny("")
+suspend fun suspendAny(): Any = ICAny("")
+suspend fun <T> suspendGeneric(x: T): T = x
+
+fun useICAny(x: ICAny) {}
+fun useAny(x: Any) {}
+
+suspend fun test() {
+    useICAny(suspendICAny())
+    useICAny(suspendGeneric(ICAny("")))
+    useAny(suspendAny())
+    useAny(suspendICAny())
+}
+
+// -- 1 in 'suspendAny(): Any = ICAny("")'
+// -- 1 in 'useAny(suspendICAny())'
+// -- 1 in 'suspendGeneric(ICAny(""))'
+// 3 INVOKESTATIC ICAny\.box-impl
+
+// -- 1 in 'useICAny(suspendGeneric(ICAny("")))
+// -- 1 in 'equals-impl' for ICAny
+// 2 INVOKEVIRTUAL ICAny\.unbox-impl

compiler/testData/codegen/bytecodeText/coroutines/inlineClasses/noInlineClassBoxingInSuspendFunReturn_InlineAny.kt

@@ -0,0 +1,24 @@
+// IGNORE_BACKEND: JVM_IR
+
+inline class IC0(val x: Any) // IC0.unbox-impl in generated 'equals'
+inline class IC1(val x: IC0) // IC1.unbox-impl in generated 'equals'
+
+suspend fun suspendIC(): IC1 = IC1(IC0(""))
+suspend fun suspendAny(): Any = IC1(IC0("")) // IC1.box-impl
+suspend fun <T> suspendGeneric(x: T): T = x
+
+fun useIC(x: IC1) {}
+fun useAny(x: Any) {}
+
+suspend fun test() {
+    useIC(suspendIC())
+    useIC(suspendGeneric(IC1(IC0("")))) // IC1.box-impl, IC1.unbox-impl
+    useAny(suspendAny())
+    useAny(suspendIC()) // IC1.box-impl
+}
+
+// 0 INVOKESTATIC IC0\.box-impl
+// 3 INVOKESTATIC IC1\.box-impl
+
+// 1 INVOKEVIRTUAL IC0\.unbox-impl
+// 2 INVOKEVIRTUAL IC1\.unbox-impl