[FIR] Fix default message for PRIVATE_CLASS_MEMBER_FROM_INLINE

Error message was only printing the calling inline function and not the
class member being accessed. Make sure both pieces for diagnostic
information are included in the error message.

#KT-58972 Fixed

compiler/testData/diagnostics/tests/inline/nonPublicMember/kt55179.kt

@@ -1,5 +1,6 @@
 // ISSUE: KT-55179
 // SKIP_TXT
+// !RENDER_DIAGNOSTICS_FULL_TEXT
 
 private class Foo {
     companion object {