exception: switch from org.freedesktop to openbmc

sd-bus makes it nearly impossible to differentiate between
`org.freedesktop.DBus.Error` types caused by the sd-bus library or
returned by an application.  Therefore, we should migrate to having no
error types of `org.freedesktop.DBus.*`, in order to allow clients to
differentiate.  There are no cases currently where code is explicitly
looking for `FileNotFound`, so there should not be any dependencies on
this change.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I414b8a19556a8608561fee912733e04bea1a2b3e
diff --git a/src/main.cpp b/src/main.cpp
index 896d248..5bbb0a3 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -28,7 +28,7 @@
 {
     const char* name() const noexcept override
     {
-        return "org.freedesktop.DBus.Error.FileNotFound";
+        return "xyz.openbmc_project.Common.Error.ResourceNotFound";
     };
     const char* description() const noexcept override
     {
@@ -36,8 +36,8 @@
     };
     const char* what() const noexcept override
     {
-        return "org.freedesktop.DBus.Error.FileNotFound: "
-               "The requested object was not found";
+        return "xyz.openbmc_project.Common.Error.ResourceNotFound: "
+               "The resource is not found.";
     };
 };