mmctl: user preferences (#25721)

* add support for get/set/delete user preferences

* make mmctl-docs

* make --category required

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/cmd/mmctl/docs/mmctl_user_preference_delete.rst

@@ -0,0 +1,53 @@
+.. _mmctl_user_preference_delete:
+
+mmctl user preference delete
+----------------------------
+
+Delete a specific user preference
+
+Synopsis
+~~~~~~~~
+
+
+Delete a specific user preference
+
+::
+
+  mmctl user preference delete --category [category] --name [name] [users] [flags]
+
+Examples
+~~~~~~~~
+
+::
+
+  preference delete --category display_settings --name use_military_time user@example.com
+
+Options
+~~~~~~~
+
+::
+
+  -c, --category string   The category of the preference
+  -h, --help              help for delete
+  -n, --name string       The name of the preference
+
+Options inherited from parent commands
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+::
+
+      --config string                path to the configuration file (default "$XDG_CONFIG_HOME/mmctl/config")
+      --disable-pager                disables paged output
+      --insecure-sha1-intermediate   allows to use insecure TLS protocols, such as SHA-1
+      --insecure-tls-version         allows to use TLS versions 1.0 and 1.1
+      --json                         the output format will be in json format
+      --local                        allows communicating with the server through a unix socket
+      --quiet                        prevent mmctl to generate output for the commands
+      --strict                       will only run commands if the mmctl version matches the server one
+      --suppress-warnings            disables printing warning messages
+
+SEE ALSO
+~~~~~~~~
+
+* `mmctl user preference <mmctl_user_preference.rst>`_ 	 - Manage user preferences
+