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/test/fuzz/fuzz.cpp

@@ -4,6 +4,7 @@
 
 #include <test/fuzz/fuzz.h>
 
+#include <fs.h>
 #include <netaddress.h>
 #include <netbase.h>
 #include <test/util/setup_common.h>
@@ -12,9 +13,12 @@
 
 #include <cstdint>
 #include <exception>
+#include <fstream>
 #include <functional>
+#include <map>
 #include <memory>
 #include <string>
+#include <tuple>
 #include <unistd.h>
 #include <vector>
 
@@ -80,7 +84,7 @@ void initialize()
     }
     if (const char* out_path = std::getenv("WRITE_ALL_FUZZ_TARGETS_AND_ABORT")) {
         std::cout << "Writing all fuzz target names to '" << out_path << "'." << std::endl;
-        fsbridge::ofstream out_stream{out_path, std::ios::binary};
+        std::ofstream out_stream{out_path, std::ios::binary};
         for (const auto& t : FuzzTargets()) {
             if (std::get<2>(t.second)) continue;
             out_stream << t.first << std::endl;