winbindd: Add support for name aliasing.
* Add support user and group name aliasing by expanding
the ws_name_replace() and ws_name_return() functions.
The lookup path is
aliases -> qualified name -> SID
SID -> fully qualified name -> alias
In other words, the name aliasing support is a thin layer
built on top of SID/NAME translation.
* Rename the ws_name_XX() functions to normalize_name_map()
and normalize_name_unmap(). Chaneg interface to return
NTSTATUS rather than char *.
* Add associated cache validation functions.