Migrate Get/GetFromMaster methods from ChannelStore to return error interface (#14688)

* Advances

* Migration finished

* Rename err to normalized error

* fix imports

* Renamed key

* Renamed key

* Suggestions

* Fix i18n

* Fix tests

Co-authored-by: Jesús Espino <jespinog@gmail.com>
Co-authored-by: Agniva De Sarker <agnivade@yahoo.co.in>

store/timer_layer.go

@@ -600,7 +600,7 @@ func (s *TimerLayerChannelStore) Delete(channelId string, time int64) *model.App
 	return resultVar0
 }
 
-func (s *TimerLayerChannelStore) Get(id string, allowFromCache bool) (*model.Channel, *model.AppError) {
+func (s *TimerLayerChannelStore) Get(id string, allowFromCache bool) (*model.Channel, error) {
 	start := timemodule.Now()
 
 	resultVar0, resultVar1 := s.ChannelStore.Get(id, allowFromCache)
@@ -952,7 +952,7 @@ func (s *TimerLayerChannelStore) GetForPost(postId string) (*model.Channel, *mod
 	return resultVar0, resultVar1
 }
 
-func (s *TimerLayerChannelStore) GetFromMaster(id string) (*model.Channel, *model.AppError) {
+func (s *TimerLayerChannelStore) GetFromMaster(id string) (*model.Channel, error) {
 	start := timemodule.Now()
 
 	resultVar0, resultVar1 := s.ChannelStore.GetFromMaster(id)