API: libcrmcluster: Drop enum crm_node_flags and all its values

Replace it with an internal enum pcmknode_status_flags. Also change
pcmknode_status_t:flags from uint64_t to uint32_t since there are few
values.

This breaks API backward compatibility.

Ref T793

Signed-off-by: Reid Wahl <nrwahl@protonmail.com>