refactor: replace boost::filesystem with std::filesystem

Warning: Replacing fs::system_complete calls with fs::absolute calls
in this commit may cause minor changes in behaviour because fs::absolute
no longer strips trailing slashes; however these changes are believed to
be safe.

Co-authored-by: Russell Yanofsky <russ@yanofsky.org>
Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>

src/qt/walletframe.cpp

@@ -4,6 +4,7 @@
 
 #include <qt/walletframe.h>
 
+#include <fs.h>
 #include <node/ui_interface.h>
 #include <psbt.h>
 #include <qt/guiutil.h>
@@ -14,6 +15,8 @@
 #include <util/system.h>
 
 #include <cassert>
+#include <fstream>
+#include <string>
 
 #include <QApplication>
 #include <QClipboard>
@@ -210,7 +213,7 @@ void WalletFrame::gotoLoadPSBT(bool from_clipboard)
             Q_EMIT message(tr("Error"), tr("PSBT file must be smaller than 100 MiB"), CClientUIInterface::MSG_ERROR);
             return;
         }
-        fsbridge::ifstream in{filename.toLocal8Bit().data(), std::ios::binary};
+        std::ifstream in{filename.toLocal8Bit().data(), std::ios::binary};
         data = std::string(std::istreambuf_iterator<char>{in}, {});
     }