[aider assisted] MM-61888: Add ClientSideUserIds field to MetricsSettings (#30127)

We add a new config setting to allow the admin to set a fixed
list of userIDs to track for all client side webapp metrics.

This gives the admin to get a deeper look at how the application
is behaving for a single user.

A new section in the system console is also added for the user
to edit this setting from the UI.

https://mattermost.atlassian.net/browse/MM-61888

```release-note
A new config setting MetricsSettings.ClientSideUserIds is added
where you can set the user ids you want to track for client side webapp
metrics.
```

* fix lint errors

```release-note
NONE
```

* fixing tests

```release-note
NONE
```

server/i18n/en.json

@@ -9076,6 +9076,14 @@
     "id": "model.config.is_valid.message_export.global_relay.smtp_username.app_error",
     "translation": "Message export job GlobalRelaySettings.SmtpUsername must be set."
   },
+  {
+    "id": "model.config.is_valid.metrics_client_side_user_id.app_error",
+    "translation": "Invalid client side user id: {{.Id}}"
+  },
+  {
+    "id": "model.config.is_valid.metrics_client_side_user_ids.app_error",
+    "translation": "Number of elements in ClientSideUserIds {{.CurrentLength}} is higher than maximum limit of {{.MaxLength}}."
+  },
   {
     "id": "model.config.is_valid.move_thread.domain_invalid.app_error",
     "translation": "Invalid domain for move thread settings"
@@ -9426,7 +9434,7 @@
   },
   {
     "id": "model.incoming_hook.id.app_error",
-    "translation": "Invalid Id."
+    "translation": "Invalid Id: {{.Id}}."
   },
   {
     "id": "model.incoming_hook.parse_data.app_error",