MM-22051: Remove ToJson from model (part 1) (#18005)

https://mattermost.atlassian.net/browse/MM-22051

```release-note
Removed the following methods/functions:
(ad *AccessData) ToJson()
(ar *AccessResponse) ToJson()
(ar *AnalyticsRow) ToJson()
(ar AnalyticsRows) ToJson()
(o *Audit) ToJson()
(o Audits) ToJson()
(ad *AuthData) ToJson()
(ar *AuthorizeRequest) ToJson()
(o *ChannelPatch) ToJson()
(o *ChannelsWithCount) ToJson()
(o *ChannelCounts) ToJson()
(o *ChannelData) ToJson()
(o *ChannelMembers) ToJson()
(o *ChannelUnread) ToJson()
(o *ChannelUnreadAt) ToJson()
(o *ChannelStats) ToJson()
(o *ChannelView) ToJson()
(o *ChannelViewResponse) ToJson()
(o *ClusterDiscovery) ToJson()
(ci *ClusterInfo) ToJson()
(cs *ClusterStats) ToJson()
(o *Command) ToJson()
CommandListToJson(l []*Command) string
(o *CommandArgs) ToJson()
(cmr *CommandMoveRequest) ToJson()
(o *CommandResponse) ToJson()
(c *Compliance) ToJson()
(c Compliances) ToJson()
(o *Config) ToJson()
EmojiListToJson(emojiList []*Emoji)
```

model/command.go

@@ -43,22 +43,12 @@ type Command struct {
 	AutocompleteIconData string `db:"-" json:"autocomplete_icon_data,omitempty"`
 }
 
-func (o *Command) ToJson() string {
-	b, _ := json.Marshal(o)
-	return string(b)
-}
-
 func CommandFromJson(data io.Reader) *Command {
 	var o *Command
 	json.NewDecoder(data).Decode(&o)
 	return o
 }
 
-func CommandListToJson(l []*Command) string {
-	b, _ := json.Marshal(l)
-	return string(b)
-}
-
 func CommandListFromJson(data io.Reader) []*Command {
 	var o []*Command
 	json.NewDecoder(data).Decode(&o)