Bluetooth (Windows): adds a string variant helper; removes propsys dependency

src/common/windows/variant.cpp

@@ -0,0 +1,21 @@
+#include "variant.hpp"
+
+#include <oleauto.h>
+
+FFWmiVariant::FFWmiVariant(std::initializer_list<PCWSTR> strings): FFWmiVariant()
+{
+    SAFEARRAYBOUND bound = {
+        .cElements = (ULONG) strings.size(),
+        .lLbound = 0,
+    };
+    SAFEARRAY* psa = SafeArrayCreate(VT_BSTR, 1, &bound);
+
+    LONG i = 0;
+    for (PCWSTR str : strings) {
+        SafeArrayPutElement(psa, &i, bstr_t(str));
+        ++i;
+    }
+
+    this->vt = VT_ARRAY | VT_BSTR;
+    this->parray = psa;
+}