Added a way to check Block Size, Compression Method, and Compression Level flags to dolphin-tool

New dolphin-tool command: "header"
-b / --block_size
-c / --compression
-l / --compression_level

Informative RVZ/WIA header2 value "compression_level" is now a s32 instead of a u32, because negative compression is a thing.

Speaking of, it is now possible to use negative compression levels in dolphin-tool's convert command (not the GUI, though).

Source/Core/DiscIO/TGCBlob.h

@@ -50,6 +50,7 @@ public:
   u64 GetBlockSize() const override { return 0; }
   bool HasFastRandomAccessInBlock() const override { return true; }
   std::string GetCompressionMethod() const override { return {}; }
+  std::optional<int> GetCompressionLevel() const override { return std::nullopt; }
 
   bool Read(u64 offset, u64 nbytes, u8* out_ptr) override;