Low: libcrmcommon: specify "pacemakerd" as pacemakerd IPC message protocol

... in IPC requests, instead of "crmd". This means that IPC replies will now
specify that protocol as well.

We can't require the message type to match, because pacemakerd IPC is proxied
to Pacemaker Remote nodes. Newer remote clients need to be able to connect to
an older pacemakerd that still specifies "crmd".