MM-30823: Change to idiomatic receiver names for model.PushResponse (#16348)

JIRA Ticket - https://mattermost.atlassian.net/browse/MM-30823

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

model/push_response.go

@@ -37,8 +37,8 @@ func NewErrorPushResponse(message string) PushResponse {
 	return m
 }
 
-func (me *PushResponse) ToJson() string {
-	b, _ := json.Marshal(me)
+func (pr *PushResponse) ToJson() string {
+	b, _ := json.Marshal(pr)
 	return string(b)
 }