1. vfs重构优化，统一fs模块的对外接口，减少不必要的冗余调用，由fs组件直接提供posix对外接口
  2. vfs与libc关系整理
  3. fs接口实现规范化

BREAKING CHANGE:
删除API:
int LOS_Open(const char *path, int flags, ...);
int LOS_Close(int fd);
ssize_t LOS_Read(int fd, void *buff, size_t bytes);
ssize_t LOS_Write(int fd, const void *buff, size_t bytes);
off_t LOS_Lseek(int fd, off_t off, int whence);
int LOS_Stat(const char *path, struct stat *stat);
int LOS_Statfs(const char *path, struct statfs *buf);
int LOS_Unlink(const char *path);
int LOS_Rename(const char *oldpath, const char *newpath);
int LOS_Fsync(int fd);
DIR *LOS_Opendir(const char *path);
struct dirent *LOS_Readdir(DIR *dir);
int LOS_Closedir(DIR *dir);
int LOS_Mkdir(const char *path, mode_t mode);
int LOS_Rmdir(const char *path);
int LOS_Lstat(const char *path, struct stat *buffer);
int LOS_Fstat(int fd, struct stat *buf);
int LOS_Fcntl(int fd, int cmd, ...);
int LOS_Ioctl(int fd, int req, ...);
ssize_t LOS_Readv(int fd, const struct iovec *iovBuf, int iovcnt);
ssize_t LOS_Writev(int fd, const struct iovec *iovBuf, int iovcnt);
ssize_t LOS_Pread(int fd, void *buff, size_t bytes, off_t off);
ssize_t LOS_Pwrite(int fd, const void *buff, size_t bytes, off_t off);
int LOS_Isatty(int fd);
int LOS_Access(const char *path, int amode);
int LOS_Ftruncate(int fd, off_t length);
int LOS_FsUmount(const char *target);
int LOS_FsUmount2(const char *target, int flag);
int LOS_FsMount(const char *source, const char *target,
                const char *fsType, unsigned long mountflags,
                const void *data);
int OsFcntl(int fd, int cmd, va_list ap);
int OsIoctl(int fd, int req, va_list ap);

Close #I66F6I
Signed-off-by: Narvinzzz <zhaotianyu9@huawei.com>