refs https://github.com/TryGhost/Team/issues/801
- This reverts commit de560733c5
- brings back members segment select component to post access, which allows setting access to specific labels/products
- only works behind the alpha feature flag - `multipleProducts`
refs https://github.com/TryGhost/Team/issues/581
Setting post visibility to a label results in undesirable and confusing behaviour with no good way to manage access long-term. Coupled with products being limited to a single product for now we're reverting the UI back to the "Public", "Members", and "Paid" options.
https://github.com/TryGhost/Team/issues/581
The API now supports `posts.visibility` being an NQL string as well as the special-case `'members'` and `'paid'` values so the post settings menu visibility select needs to be updated to reflect that.
- swapped visibility dropdown for two radio buttons, "Public" and "Members-only" which uses the `<GhMembersSegmentSelect>` component
- updated post model to use a `visibility-string` transform
- converts `members` and `paid` to/from the NQL equivalent for correct display in the segment select
- updated post model with two additional properties `isPublic` and `visibilitySegment`
- `isPublic` helps with the radio button display
- `visibilitySegment` allows fallback to the default content visibility setting when set to public
- added validation for `post.visibility` so we can show an error and skip saving when members-only is selected and the segment select is cleared
- deleted the now-unused `<GhPsmVisibilityInput>` component
