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/Blob.h

@@ -59,6 +59,7 @@ public:
   virtual u64 GetBlockSize() const = 0;
   virtual bool HasFastRandomAccessInBlock() const = 0;
   virtual std::string GetCompressionMethod() const = 0;
+  virtual std::optional<int> GetCompressionLevel() const = 0;
 
   // NOT thread-safe - can't call this from multiple threads.
   virtual bool Read(u64 offset, u64 size, u8* out_ptr) = 0;