Refactor: libcrmcommon, daemons: New pcmk__cluster_option_metadata()

This new function is a wrapper for pcmk__format_option_metadata() that
always uses the shared cluster_options array and its length.

Daemons can now call this function to get metadata instead of using
their local options arrays for that purpose.

Soon we'll introduce a command that outputs all cluster option metadata
directly, instead of calling daemon metadata commands.

Ref T746

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