MM-44088: Add teamID filter to channelMembers (#20176)

We add 2 new params to channel members query.
1. Filter by teamId.
2. Negate that filter.

We include some more optimizations like:
- Moved the team role checks inside the dataloader.
- Moved the channel pretty name computation inside the loader.

Now that we load less data on initial load, we can reduce
the concurrency requirement to be a bit on the safer side.

```release-note
NONE
```

api4/graphql.go

@@ -34,7 +34,7 @@ const (
 	usersLoaderCtx    ctxKey = 4
 )
 
-const loaderBatchCapacity = web.PerPageMaximum + 100
+const loaderBatchCapacity = web.PerPageMaximum
 
 //go:embed schema.graphqls
 var schemaRaw string