suites/multimds: sync with fs suites

suites/multimds: sync with fs suites

This commit synchronizes the multimds suite with the fs suite. The
basic/verify sub-suites now do the same tests except with different
cluster layouts (i.e. multiple actives). This is mostly accomplished by
symlinking parts of each sub-suite to its counterpart in the fs suite.

This commit also does a few things of note to the prior multimds suite:

o Turn on directory fragmentation.
o Add several tests from fs/basic/tasks to multimds/basic.
o Remove libcephfs as fs/basic/tasks already contain
  multimds/basic/tasks.

Prior implementation and discussion are in PR#1114: https://github.com/ceph/ceph-qa-suite/pull/1114

Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>