s3:smbd: make get_file_handle_for_metadata() public

In preperation of SMB2 AAPL create context: will be used when
enumerating directories in order to internally retrieve stream
information of filesystem objects.

Signed-off-by: Ralph Boehme <rb@sernet.de>
s3: smbd: add SMB2 AAPL create context defines and option flags

smb2_crtctx_aapl_readdir_attr = true | false

  When used several fields in an SMB2/FIND reply are repurposed
  returning Mac specific file attributes including esource fork
  length, unix mode and max access.

Signed-off-by: Ralph Boehme <rb@sernet.de>
s3:smbd: SMB2 AAPL create context implementation

Signed-off-by: Ralph Boehme <rb@sernet.de>
s3:smbd: flags for NFS ACE in AAPL create context

Add define and flag for NFS ACE in AAPL create context. With this
extension, a client can use get_info(sec)/set_info(sec) for

o retrieving UNIX uid,gid and mode of a file with get_info
o modifying UNIX mode with set_info

Signed-off-by: Ralph Boehme <rb@sernet.de>
libcli/security: add NFS SID mappings

Signed-off-by: Ralph Boehme <rb@sernet.de>
vfs_fruit: SMB2 AAPL create_context: NFS ACEs

Return uid, gid and mode in NFS ACEs append them to the ACL we get
from the next VFS module.

Extract mode from client NFS ACE and apply it.

Signed-off-by: Ralph Boehme <rb@sernet.de>