Don't use a hard-coded user-agent for placefiles, add DPI parameter

wxdata/source/scwx/network/cpr.cpp

@@ -0,0 +1,26 @@
+#include <scwx/network/cpr.hpp>
+
+namespace scwx
+{
+namespace network
+{
+namespace cpr
+{
+
+static const std::string logPrefix_ = "scwx::network::cpr";
+
+static ::cpr::Header header_ {};
+
+::cpr::Header GetHeader()
+{
+   return header_;
+}
+
+void SetUserAgent(const std::string& userAgent)
+{
+   header_.insert_or_assign("User-Agent", userAgent);
+}
+
+} // namespace cpr
+} // namespace network
+} // namespace scwx