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_response.go

@@ -32,11 +32,6 @@ type CommandResponse struct {
 	ExtraResponses   []*CommandResponse `json:"extra_responses"`
 }
 
-func (o *CommandResponse) ToJson() string {
-	b, _ := json.Marshal(o)
-	return string(b)
-}
-
 func CommandResponseFromHTTPBody(contentType string, body io.Reader) (*CommandResponse, error) {
 	if strings.TrimSpace(strings.Split(contentType, ";")[0]) == "application/json" {
 		return CommandResponseFromJson(body)