MM-21357: Use typed constant for channel types (#17928)

* MM-21357: Use typed constant for channel types

https://mattermost.atlassian.net/browse/MM-21357

```release-note
- Introduced a new type ChannelType for all channel types.
- Updated the Client4.UpdateChannelPrivacy method to ChannelType.
```

* Address review comments

```release-note
NONE
```

* telemetry fix

```release-note
NONE
```

store/opentracinglayer/opentracinglayer.go

@@ -552,7 +552,7 @@ func (s *OpenTracingLayerChannelStore) AnalyticsDeletedTypeCount(teamID string,
 	return result, err
 }
 
-func (s *OpenTracingLayerChannelStore) AnalyticsTypeCount(teamID string, channelType string) (int64, error) {
+func (s *OpenTracingLayerChannelStore) AnalyticsTypeCount(teamID string, channelType model.ChannelType) (int64, error) {
 	origCtx := s.Root.Store.Context()
 	span, newCtx := tracing.StartSpanWithParentByContext(s.Root.Store.Context(), "ChannelStore.AnalyticsTypeCount")
 	s.Root.Store.SetContext(newCtx)