[MM-23264] Get channel member counts by group (#14068)

* MM-23264 Add api endpoint for get groups with members in channel

Add store tests

Add tests for api func

Gofmt

Apply changes from code review

* MM-23264 Make store layers

* MM-23264 Check read permission on channel member counts

* Trigger CI

i18n/en.json

@@ -243,6 +243,10 @@
     "id": "api.channel.change_channel_privacy.public_to_private",
     "translation": "This channel has been converted to a Private Channel."
   },
+  {
+    "id": "api.channel.channel_member_counts_by_group.license.error",
+    "translation": "Your license does not support groups"
+  },
   {
     "id": "api.channel.convert_channel_to_private.default_channel_error",
     "translation": "This default channel cannot be converted into a private channel."