MM42267: Add member count in the browse channel modal (#23800)

* add base for calling the endpoint

* add endpoint and handler

* update store and layers

* call the endpoint

* align types

* update app layers

* generate mocks

* complete handler

* finish store query

* add todos

* add ui for member count

* add selector

* add a todo

* add cache layer

* optimize calls in FE

* handle invalidation of the cache

* fix go style

* fix test

* use existing channel layer count

* fix import error

* delete unnecessary code

* write tests for channel cache layer

* fix testname

* fix mocks

* fix cache layer test

* fix a test

* really fix the test

* write more tests for server

* address PR comments

* remove comment

* rename more_channels to browse_channels

* fix style

* update snapshot

* add translations

* Revert "add translations"

This reverts commit 56476a5dabe357703ef02be9a38b3e88f5c8b1e7.

* add only related translations

* address PR review points

* add test

* fix test

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/store/timerlayer/timerlayer.go

@@ -1184,6 +1184,22 @@ func (s *TimerLayerChannelStore) GetChannelsByUser(userID string, includeDeleted
 	return result, err
 }
 
+func (s *TimerLayerChannelStore) GetChannelsMemberCount(channelIDs []string) (map[string]int64, error) {
+	start := time.Now()
+
+	result, err := s.ChannelStore.GetChannelsMemberCount(channelIDs)
+
+	elapsed := float64(time.Since(start)) / float64(time.Second)
+	if s.Root.Metrics != nil {
+		success := "false"
+		if err == nil {
+			success = "true"
+		}
+		s.Root.Metrics.ObserveStoreMethodDuration("ChannelStore.GetChannelsMemberCount", success, elapsed)
+	}
+	return result, err
+}
+
 func (s *TimerLayerChannelStore) GetChannelsWithCursor(teamId string, userId string, opts *model.ChannelSearchOpts, afterChannelID string) (model.ChannelList, error) {
 	start := time.Now()