meteor3: purge dead client packages — web UI renders on 3.1

alanning:roles removed (client crashed the whole bundle; plain user.roles
checks instead), selaias:cookie-consent replaced by in-repo React banner,
publish-performant-counts vendored with countAsync, Meteor.autorun dropped
(App)/Tracker.autorun (FiresMap), and the map publications not covered by
the REST smoke (activefiresmyloc, activefiresunionmyloc, fireAlerts,
oauth.verifyConfiguration) converted to async APIs.

Verified in browser: / and /fires render with map + cookie banner, zero
uncaught exceptions. REST smoke byte-identical (12/12).

packages/publish-performant-counts/server.js

@@ -0,0 +1,37 @@
+/* global Counter:true */
+
+Counter = function (name, cursor, interval) {
+  this.name = name;
+  this.cursor = cursor;
+  this.interval = interval || 1000 * 10;
+  this._collectionName = 'counters-collection';
+};
+
+// every cursor must provide a collection name via this method
+Counter.prototype._getCollectionName = function () {
+  return `counter-${this.name}`;
+};
+
+// the api to publish (async: Meteor 3 awaits _publishCursor)
+Counter.prototype._publishCursor = async function (sub) {
+  const self = this;
+
+  sub.added(self._collectionName, self.name, { count: await self.cursor.countAsync() });
+
+  const handler = Meteor.setInterval(async () => {
+    try {
+      const count = await self.cursor.countAsync();
+      sub.changed(self._collectionName, self.name, { count });
+    } catch (e) {
+      // transient db error: retry on the next tick
+    }
+  }, this.interval);
+
+  sub.onStop(() => {
+    Meteor.clearInterval(handler);
+  });
+
+  return {
+    stop: sub.onStop.bind(sub)
+  };
+};