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/authorize.go

@@ -4,7 +4,6 @@
 package model
 
 import (
-	"encoding/json"
 	"net/http"
 )
 
@@ -114,16 +113,6 @@ func (ad *AuthData) PreSave() {
 	}
 }
 
-func (ad *AuthData) ToJson() string {
-	b, _ := json.Marshal(ad)
-	return string(b)
-}
-
-func (ar *AuthorizeRequest) ToJson() string {
-	b, _ := json.Marshal(ar)
-	return string(b)
-}
-
 func (ad *AuthData) IsExpired() bool {
 	return GetMillis() > ad.CreateAt+int64(ad.ExpiresIn*1000)
 }