chore(libvideo2x)!: replace the C API with C++ API (#1245)

* chore(libvideo2x)!: replace the C API with C++ API
* fix: convert wide string to u8 for av_opt_set
* style: removed unnecessary enum and struct specifiers

Signed-off-by: k4yt3x <i@k4yt3x.com>

include/libvideo2x/logging.h

@@ -0,0 +1,23 @@
+#ifndef LOGGING_H
+#define LOGGING_H
+
+#include <optional>
+
+#include "fsutils.h"
+
+enum class Libvideo2xLogLevel {
+    Unknown,
+    Trace,
+    Debug,
+    Info,
+    Warning,
+    Error,
+    Critical,
+    Off
+};
+
+void set_log_level(Libvideo2xLogLevel log_level);
+
+std::optional<Libvideo2xLogLevel> find_log_level_by_name(const StringType &log_level_name);
+
+#endif  // LOGGING_H