FS-10554: Refactor conference vid-res-id command, add 'force' option

FS-10554: Refactor conference vid-res-id command, add 'force' option

The 'conference vid-res-id' sub command previously used the CONF_API_SUB_MEMBER_TARGET
command parsing strategy. The standard options exposed by that strategy didn't make
sense for this sub command, so it's now been switched to use the CONF_API_SUB_ARGS_SPLIT
command parsing strategy.

A third, optional 'force' argument has also been added. The default behavior of the
command is to toggle the user in and out of a reservation slot, use the force argument
to ensure the user is placed into the reservation slot provided.

The new signature of the sub command is:

  vid-res-id <member_id> <val>|clear [force]