MM42267: Add member count in the browse channel modal (#23800)

* add base for calling the endpoint

* add endpoint and handler

* update store and layers

* call the endpoint

* align types

* update app layers

* generate mocks

* complete handler

* finish store query

* add todos

* add ui for member count

* add selector

* add a todo

* add cache layer

* optimize calls in FE

* handle invalidation of the cache

* fix go style

* fix test

* use existing channel layer count

* fix import error

* delete unnecessary code

* write tests for channel cache layer

* fix testname

* fix mocks

* fix cache layer test

* fix a test

* really fix the test

* write more tests for server

* address PR comments

* remove comment

* rename more_channels to browse_channels

* fix style

* update snapshot

* add translations

* Revert "add translations"

This reverts commit 56476a5dabe357703ef02be9a38b3e88f5c8b1e7.

* add only related translations

* address PR review points

* add test

* fix test

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/i18n/en.json

@@ -4739,6 +4739,14 @@
     "id": "app.channel.get_channels_by_ids.not_found.app_error",
     "translation": "No channel found."
   },
+  {
+    "id": "app.channel.get_channels_member_count.existing.app_error",
+    "translation": "Unable to find member count for given channels."
+  },
+  {
+    "id": "app.channel.get_channels_member_count.find.app_error",
+    "translation": "Unable to find member count."
+  },
   {
     "id": "app.channel.get_deleted.existing.app_error",
     "translation": "Unable to find the existing deleted channel."