Add code for EnstoreFileReader and EnstoreReadSession.

common/dataStructures/LabelFormat.hpp

tapeserver/castor/tape/tapeserver/file/CMakeLists.txt

...r/castor/tape/tapeserver/file/CpioFileHeaderStructure.cpp

tapeserver/castor/tape/tapeserver/file/EnstoreFileReader.cpp

tapeserver/castor/tape/tapeserver/file/EnstoreFileReader.hpp

...server/castor/tape/tapeserver/file/EnstoreReadSession.cpp

...server/castor/tape/tapeserver/file/EnstoreReadSession.hpp

tapeserver/castor/tape/tapeserver/file/FileReader.hpp

tapeserver/castor/tape/tapeserver/file/FileReaderFactory.cpp

...server/castor/tape/tapeserver/file/ReadSessionFactory.cpp