LU-16134 utils: un-deprecate 'lctl set_param -F'

LU-16134 utils: un-deprecate 'lctl set_param -F'

The "lctl set_param -F" command was accidentally disabled in 2.16 due
to a mis-merge between two in-flight patches.  Restore this command.

Change some functions to use "const char" for string arguments.

Add an example usage of "lctl set_param -F" in the lctl-set_param.8
man page, and update it to match style guidelines.  Add descriptions
of the usage examples in the EXAMPLES section.

Update checkpatch-man.pl to quiet spurious warnings about examples
with client#, mgs#, mds#, or oss# in the command-line prompt text.

Test-Parameters: trivial
Test-Parameters: testlist=conf-sanity env=ONLY=123 combinedmdsmgs=false
Test-Parameters: testlist=conf-sanity env=ONLY=123 combinedmdsmgs=true
Fixes: 8be38f4bd8 ("LU-11077 utils: move get/set/list_param into own file")
Fixes: 29cfdc2f1e ("LU-16134 utils: adds lctl apply_yaml")
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I7e8140bf5e1c5747df4785539a6fda491d500c1e
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58532
Tested-by: Maloo <maloo@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Alexander Boyko <alexander.boyko@hpe.com>