Process user-specific information into different forms

[wildlarva]

Is your feature request related to a problem? Please describe.
Some users need to define user-specific information for generating a decoder and process it into different forms before generation. Currently, the mcdecoder cannot process user-specific information before generation,

Describe the solution you'd like
Add a functionality to import user code to process user-specific information into a different form.

Possible implementations for this are:

• Define a python hook function to process user-specific information and refer it from MC description
  • python config file

    from mcdecoder.core import InstructionDecoder
    
    def process_instruction(instruction: InstructionDecoder) -> None:
      instruction.extras = ...

  • MC description

    decoder:
      process_instruction_hook: process_instruction

• Define a python hook function to process user-specific information and register to mcdecoder
  • python config file

    from mcdecoder.core import InstructionDecoder, Environment
    
    # define a hook function
    def process_instruction(instruction: InstructionDecoder) -> None:
      instruction.extras = ...
    
    # register a hook function to the environment
    Environment.add_process_instruction_hook(process_instruction)

Describe alternatives you've considered
N/A

Additional context
N/A