add generic and improved NFS support with initial support for both FreeBSD and Linux (#15906)

* add nfs-shared.inc.php

* add nfs poller

* polling now works

* add nfs.inc.php page

* mount options works now

* format cleanup

* add some missing items to the stats

* commit work from last night so I can swap over to ldap

* add gauge support

* save the OS type for it

* more work on NFS stuff

* more nfs work

* display cleanup some

* more nfs work

* update docs for NFS

* add nfs_server_rpc

* style fix

* add snmprec file

* more test stuff

* data cleanup

* style cleanup

* more style fix

* another style fix

* add deleted_at

* add client_rpc_info_calls

* more test tweaks

* more tweaks

* set two items as gauges that should be gauges

* convert a few more things from counters to gauges

* a few more tweaks for NFSv4

LibreNMS/Util/StringHelpers.php

@@ -60,6 +60,7 @@ class StringHelpers
             'mojo_cape_submit' => 'Mojo CAPE Submit',
             'mailcow-postfix' => 'mailcow-dockerized postfix',
             'mysql' => 'MySQL',
+            'nfs' => 'NFS',
             'nfs-server' => 'NFS Server',
             'nfs-stats' => 'NFS Stats',
             'nfs-v3-stats' => 'NFS v3 Stats',