Refactor: libcrmcommon: use original message type in replies

Previously, all created messages and replies hardcoded PCMKVALUE_CRMD as the
message type (protocol identifier). Replies should always use the same message
type as the original request, so do that instead of hardcoding the value,
defaulting to PCMKVALUE_CRMD to preserve existing behavior.

This has no effect until we change request message types, which is planned.