Introduce coroutine support (util/coro.hpp)

Implement coroutine types `lazy` and `generator` in stx namespace.
Implement fs::list_dir_recursively.

Utilities/File.cpp

@@ -9,6 +9,7 @@
 #include <map>
 
 #include "util/asm.hpp"
+#include "util/coro.hpp"
 
 using namespace std::literals::string_literals;
 
@@ -1182,7 +1183,7 @@ fs::file::file(const std::string& path, bs_t<open_mode> mode)
 
 			for (const char* data = static_cast<const char*>(buffer); count;)
 			{
-				const DWORD size = static_cast<DWORD>(std::min<u64>(count, DWORD{umax} & -4096)); 
+				const DWORD size = static_cast<DWORD>(std::min<u64>(count, DWORD{umax} & -4096));
 
 				DWORD nwritten = 0;
 				ensure(WriteFile(m_handle, data, size, &nwritten, nullptr)); // "file::write"
@@ -2039,6 +2040,30 @@ bool fs::pending_file::commit(bool overwrite)
 	return false;
 }
 
+stx::generator<fs::dir_entry&> fs::list_dir_recursively(std::string path)
+{
+	for (auto& entry : fs::dir(path))
+	{
+		if (entry.name == "." || entry.name == "..")
+		{
+			continue;
+		}
+
+		std::string new_path = path_append(path, entry.name);
+
+		if (entry.is_directory)
+		{
+			for (auto& nested : fs::list_dir_recursively(new_path))
+			{
+				co_yield nested;
+			}
+		}
+
+		entry.name = std::move(new_path);
+		co_yield entry;
+	}
+}
+
 template<>
 void fmt_class_string<fs::seek_mode>::format(std::string& out, u64 arg)
 {