LibImage: Start work on PNG decoding

This patch adds PNG decoder that currently only inflates the PNG's zlib
deflate stream

LibImage/include/LibImage/PNG.h

@@ -0,0 +1,11 @@
+#include <BAN/ByteSpan.h>
+
+#include <LibImage/Image.h>
+
+namespace LibImage
+{
+
+	bool probe_png(BAN::ConstByteSpan);
+	BAN::ErrorOr<BAN::UniqPtr<Image>> load_png(BAN::ConstByteSpan);
+
+}