LU-16667 build: struct mnt_idmap, linux/filelock.h

LU-16667 build: struct mnt_idmap, linux/filelock.h

Linux commit v6.2-rc3-9-g5970e15dbcfe
  filelock: move file locking definitions to separate
            header file

Add configure test for linux/filelock.h and include it
where needed.

linux kernel v6.2-rc1-4-gb74d24f7a74f
  fs: port ->getattr() to pass mnt_idmap
linux kernel v6.2-rc1-3-gc1632a0f1120
  fs: port ->setattr() to pass mnt_idmap

Add a configure test for mnt_idmap and fallback to using
user_namespace for older kernels.

Test-Parameters: trivial
HPE-bug-id: LUS-11557
Signed-off-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Change-Id: Ib8cbb3157fb11b4f1fc55f1626c2998cb202bd8c
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50420
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Deiter <alex.deiter@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>