refs https://github.com/TryGhost/Admin/pull/2227
A continuation of #2227 that runs the native classes codemod against app/serializers.
Most of the serializers that are trying to be transformed are failing with the same issue:
```
Validation errors:
[attrs]: Transform not supported - value is of type object. For more details: eslint-plugin-ember/avoid-leaking-state-in-ember-objects
2022-02-02T05:54:58.571Z [warn] [app/serializers/role.js]: FAILURE
```
refs TryGhost/Team#1071
Specific tier visibility for a post was previously stored in `visibility` column directly, which had a limitation of 50 charts. Going forward, for the specific tiers visibility of post/page, we use `tiers` array in API that contains list of tiers with access for post. This change -
- replaces `filter` type to `tiers` for visibility
- adds new visibility filter segment component in post settings menu which stores array of tiers instead of nql string for visibility
- updates serializer and model for post/page
- updates tests
refs https://github.com/TryGhost/Team/issues/998
- posts have a new `email_only` property for an alpha feature but that is not a valid property for pages
- our pages model and serializers currently inherit from the post model/serializer so when saving the new property is triggering a "no additional properties" validation error
- updating the pages serializer to remove the new property means the pages add/edit API requests are valid again
no issue
- added `page` model
- removed `page` param from Post model
- added pages screen with associated links
- added `:type` param to editor screens to work with the right models
- removed post<->page toggle and associated tour item
