Custom homepage (#30545)

* Adding admin settings

* updating homepage

* permissions

* Include custom homepage on current user

Response from `/api/user/current/` now always includes a key
`custom_homepage`. It is nil unless `custom-homepage` setting is true
and `custom-homepage-dashboard` is set to an id that is a valid
dashboard that the user can read. (note this includes archived
dashboards). In this circumstance, the response will be

```
  ...
  "custom_homepage": {
    "dashboard_id": 87
  },
  ...
```

* adding unit tests

* Homepage CTA

* cleanup and types

* e2e tests, small adustments

* lint

* type fix

* Editing Dashboard Reminder

* fixing unit test

* ensure custom homepage dashboard exists and is not archived

* handling dashboard archived scenario, use-dashboard-query

* polish

* Copy updates, removing personal collections from picker

* PR Feedback

* CI checks

* PR Feedback

* Adding default filter function

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Co-authored-by: dan sutton <dan@dpsutton.com>