fsnotify: split fsnotify_perm() into two hooks

fsnotify: split fsnotify_perm() into two hooks

We would like to make changes to the fsnotify access permission hook -
add file range arguments and add the pre modify event.

In preparation for these changes, split the fsnotify_perm() hook into
fsnotify_open_perm() and fsnotify_file_perm().

This is needed for fanotify "pre content" events.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231212094440.250945-4-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>