Remove mutex lock from WorkspaceGroup::createInfoNode

This is called by the base Workspace::addInfoNodeTo method when the object
is a WorkspaceGroup. The base method locks the workspace RWLock but then
for a group the overloaded createInfoNode was then also locking a mutex
that causes a dead-lock while both locks wait for each other to release.
Refs #7677
Fix a minor bug in naming of group members in ChopData.

The ADS tries to add the members of a group to the ADS if they don't have
a name. It's naming scheme is different to what ChopData does and
so you effectively end up with an object having two names. The dock
then reports workspaces that don't exist and you can't delete them.
Refs #7677
Handle locking of run/sample in ExperimentInfo.

This way we can use a more general mutex rather than the specific
critical section used in cow_ptr. Also move some calls that access
the object directly to use the accessor methods that should prevent
access to the object while it is being copied.
Refs #7677
Merge remote-tracking branch 'origin/bugfix/7677_segfault_c2e'