FileSystemLib provides generic interfaces to access file system and
its files as a abstraction of FatLib/ExtLib.
- Added CloseFileSystem
If there are opened files in a specific filesystem, those files
will be de-allocated in CloseFileSystem.
- Added OpenFile/GetFileSize/ReadFile/CloseFile
The ReadFile() does not allocate any memory for the file content.
The caller of OpenFile() MUST allocate necessary memory before
calling ReadFile().
Signed-off-by: Aiden Park <aiden.park@intel.com>