JVM IR: substitute generic type for inline class replacement function calls

The main change here is in `JvmInlineClassLowering.visitFunctionAccess`,
where we now store the substituted return type of the function as the
type of the call expression. Without it, the call could have a
meaningless type, e.g. some `T` which is inaccessible at that place, and
that could backfire in subsequent lowerings in codegen. For example, in
the `stringPlus.kt` test, it would prevent the code in
`FlattenStringConcatenationLowering.isStringPlusCall` from recognizing
and replacing the `String.plus` call, leading to a codegen exception.

Other changes are mostly cosmetics to make the code similar to
`visitFunctionReference`, and preventive optimizations for the case when
the substitution map is empty.

compiler/ir/backend.common/src/org/jetbrains/kotlin/ir/util/IrTypeUtils.kt

@@ -80,7 +80,7 @@ fun IrType.substitute(params: List<IrTypeParameter>, arguments: List<IrType>): I
     substitute(params.map { it.symbol }.zip(arguments).toMap())
 
 fun IrType.substitute(substitutionMap: Map<IrTypeParameterSymbol, IrType>): IrType {
-    if (this !is IrSimpleType) return this
+    if (this !is IrSimpleType || substitutionMap.isEmpty()) return this
 
     val newAnnotations = annotations.map { it.deepCopyWithSymbols() }