Add optional info function to redis_module macro

[oshadmi]

Adding a new argument to redis_module macro, which allows specifying a callback function for adding specific module information to the INFO command,
e.g., INFO MODULES,
or INFO <module_name>, for example:

127.0.0.1:6379> INFO hello
# hello_hello
hello_field:value
127.0.0.1:6379> 

(this is in addition to the already used callback function for adding stack trace on panic/crash)