Add support for class file disassembly

[algomaster99]

Proposing a dissassembler for classfiles in diffr. It only gets the list of UTF8 constant and list of opcodes in functions and compares them. How it may benefit over javap -verbose -constants -s -l -private:

1. We can ensure that the order of constant pool does not matter.
2. We can ignore comparison of tables like StackMapTable (used for type checking) and debugging information.
3. Mark set of instructions (opcodes) as equivalent.

I think it would be better to have this rather than Binary files differ since we will use diffr get diff assets locally.