feat: macros that decoding arguments can set custom decoder using decode_with

[lwshang]

SDK-1924

Description

• Add decode_with hook for customizing arguments decoding.
• When the argument is empty, the macros won't generate the code which get msg_arg_data then decode as Candid.
  • The callee can send any arguments to such entry-points. And the entry-point won't waste any cycles on decoding it into '()'.
  • If it's needed, developer can still use decode_with to decode the arguments data.
• Some code cleanup for better maintainability.

How Has This Been Tested?

Added a macros e2e test.

Checklist:

• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.