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/testData/codegen/box/inlineClasses/stringPlus.kt

@@ -0,0 +1,9 @@
+// !LANGUAGE: +InlineClasses
+
+fun <T> foo(a: IC): T = a.value as T
+
+inline class IC(val value: String)
+
+fun box(): String {
+    return foo<String>(IC("O")) + "K"
+}