message: feat(base-server): async channel filter
diff: @@ -543,7 +543,7 @@ export class BaseServer {
  }
  }
  - sendAction(action, meta) {
  + async sendAction(action, meta) {
  let from = parseId(meta.id).clientId
  let ignoreClients = new Set(meta.excludeClients || [])
  ignoreClients.add(from)
  @@ -594,7 +594,7 @@ export class BaseServer {
  let filter = subscriber.filter
  if (typeof filter === 'function') {
  if (!ctx) ctx = this.createContext(action, meta)
  - filter = filter(ctx, action, meta)
  + filter = await filter(ctx, action, meta)
  }
  let client = this.clientIds.get(clientId)
  if (filter && client) {
  