crush: dump weight-set values with 'osd crush tree'

crush: dump weight-set values with 'osd crush tree'

For plain, include a column for each pool.  Show only the first weight if
it is positional.

For formatted, include the full set of weights.

As far of this we switch 'ceph osd crush tree' to have a plaintext mode.

Signed-off-by: Sage Weil <sage@redhat.com>