fio: create over-arching data placement option

fio: create over-arching data placement option

Since FDP and streams are similar, we should have an over-arching data
placement option that encompasses both of these frameworks instead of
having separate sets of similar options for FDP and streams.

With a common set of options, users will be able to select the data
placement strategy (fdp or streams), the placement identifiers to use,
and the algorithm for selecting from the list of placement identifiers.

The original set of FDP options is retained for backward compatibility.

No functional change.

Signed-off-by: Vincent Fu <vincent.fu@samsung.com>