[Fix] Fix compiler warnings in lua_logger and dkim modules

[Fix] Fix compiler warnings in lua_logger and dkim modules

Fixed incompatible pointer type warnings in lua_logger.c when converting
strings to integers by using gulong/glong types matching rspamd_strtoul/
rspamd_strtol function signatures.

Fixed enum type mismatch in dkim.c by adding RSPAMD_DKIM_KEY_INVALID to
rspamd_dkim_key_type enum and handling it in the verification switch.