Storage for files. A FileStore represents a storage pool, device,
partition, volume, concrete file system or other implementation specific means
of file storage. The FileStore for where a file is stored is obtained
by invoking the getFileStore method, or all file
stores can be enumerated by invoking the getFileStores method.
In addition to the methods defined by this class, a file store may support
one or more FileStoreAttributeView classes
that provide a read-only or updatable view of a set of file store attributes.