MM-20100: Migrate channelGuestCountsCache cache from store/sqlstore/channel_store.go to the new store/localcachelayer (#13135)

* init

* migrate

* add test

* fix channel store

* ...

* missing ')'

* change function interface

* fix build

* fix format

* Update store/localcachelayer/layer.go

Co-Authored-By: Bot from GolangCI <42910462+golangcibot@users.noreply.github.com>

* Update store/localcachelayer/channel_guest_layer_test.go

Co-Authored-By: Bot from GolangCI <42910462+golangcibot@users.noreply.github.com>

* im so confused why my builds are failing

* fix build

* format

* fix format

* add license header

* resolve some conflicts

* add test

* fix constant names

* fix more constants

* fix bugs

* delete unused constants

* Update store/localcachelayer/channel_layer.go

Co-Authored-By: Bot from GolangCI <42910462+golangcibot@users.noreply.github.com>

* typo

* another typo

* get guest

* change test

* go fmt format

* change test

* remove getcountcache

* delete method from interface

* delete method

* update test

* rerun GoLang CI

store/timer_layer.go

@@ -984,22 +984,6 @@ func (s *TimerLayerChannelStore) GetGuestCount(channelId string, allowFromCache
 	return resultVar0, resultVar1
 }
 
-func (s *TimerLayerChannelStore) GetGuestCountFromCache(channelId string) int64 {
-	start := timemodule.Now()
-
-	resultVar0 := s.ChannelStore.GetGuestCountFromCache(channelId)
-
-	elapsed := float64(timemodule.Since(start)) / float64(timemodule.Second)
-	if s.Root.Metrics != nil {
-		success := "false"
-		if true {
-			success = "true"
-		}
-		s.Root.Metrics.ObserveStoreMethodDuration("ChannelStore.GetGuestCountFromCache", success, elapsed)
-	}
-	return resultVar0
-}
-
 func (s *TimerLayerChannelStore) GetMember(channelId string, userId string) (*model.ChannelMember, *model.AppError) {
 	start := timemodule.Now()