throw on failed writing and port fs namespace changes from oxen-core

daemon/lokinet-bootstrap.cpp

@@ -70,7 +70,8 @@ main(int argc, char* argv[])
   std::string data{ss.str()};
   if (data[0] == 'l' or data[0] == 'd')
   {
-    std::ofstream ofs{outputfile};
+    fs::ofstream ofs{outputfile};
+    ofs.exceptions(fs::ofstream::failbit);
     ofs << data;
     return 0;
   }

llarp/util/fs.hpp

@@ -14,7 +14,14 @@
 namespace fs = ghc::filesystem;
 #else
 #include <filesystem>
-namespace fs = std::filesystem;
+namespace fs
+{
+  using namespace std::filesystem;
+  using ifstream = std::ifstream;
+  using ofstream = std::ofstream;
+  using fstream = std::fstream;
+}  // namespace fs
+
 #endif
 
 #ifndef _MSC_VER