make GetChannelByName take teamId first (#9134)

* make GetChannelByName take teamId first

I think it is more natural to accept `teamId`, then `channelName`,
given the pattern followed by other Plugin API methods and even the SQL
Store itself. The App layer seems unusual in accepting `channelName`
first.

This also re-generates the mocks fixing the parameter order for the
recently added `UserStatus` APIs.

* add GetChannelByNameForTeamName

app/plugin_api.go

@@ -190,10 +190,14 @@ func (api *PluginAPI) GetChannel(channelId string) (*model.Channel, *model.AppEr
 	return api.app.GetChannel(channelId)
 }
 
-func (api *PluginAPI) GetChannelByName(name, teamId string) (*model.Channel, *model.AppError) {
+func (api *PluginAPI) GetChannelByName(teamId, name string) (*model.Channel, *model.AppError) {
 	return api.app.GetChannelByName(name, teamId)
 }
 
+func (api *PluginAPI) GetChannelByNameForTeamName(teamName, channelName string) (*model.Channel, *model.AppError) {
+	return api.app.GetChannelByNameForTeamName(channelName, teamName)
+}
+
 func (api *PluginAPI) GetDirectChannel(userId1, userId2 string) (*model.Channel, *model.AppError) {
 	return api.app.GetDirectChannel(userId1, userId2)
 }