HardwareState: HWMon data reader

Ported HWMon driver from
cla-sysrepo@19163e50ab062a8b5b75f754b30c22fdbd62b03a.

In cla-sysrepo, these drivers provided a property-based API, i.e., you
asked for a specific property (i.e., a filename) and the contents of the
file was returned.

In velia, we do not need this one-by-one property access. We provide all
attributes with a single call.

Change-Id: Ife783f21d4552e3b8bc69436d2f8fa53eb6745b7
diff --git a/tests/fs-helpers/utils.h b/tests/fs-helpers/utils.h
new file mode 100644
index 0000000..93196f2
--- /dev/null
+++ b/tests/fs-helpers/utils.h
@@ -0,0 +1,4 @@
+#pragma once
+#include <filesystem>
+
+void removeDirectoryTreeIfExists(const std::filesystem::path& rootDir);