Fix #682; clink config commands don't work with a fresh Clink profile.

It's due to a bug that's existed since commit 921ca4f in 2021/09.

The `settings.set()` API cancelled itself by mistake if there was no
clink_settings file (it accidentally treated that as failure).

clink/core/src/settings.cpp

@@ -564,7 +564,7 @@ bool load(const char* file, const char* default_file)
         path::append(old_file, "settings");
         in = fopen(old_file.c_str(), "rb");
         if (in == nullptr)
-            return false;
+            return true;
         migrating = true;
     }