fix: format admin url inside forgot pw email (#11509)

### What?
Supersedes https://github.com/payloadcms/payload/pull/11490.

Refactors imports of `formatAdminURL` to import from `payload/shared`
instead of `@payloadcms/ui/shared`. The ui package now imports and
re-exports the function to prevent this from being a breaking change.

### Why?
This makes it easier for other packages/plugins to consume the
`formatAdminURL` function instead of needing to implement their own or
rely on the ui package for the utility.

packages/richtext-slate/src/cell/rscEntry.tsx

@@ -2,7 +2,7 @@ import type { DefaultServerCellComponentProps, Payload } from 'payload'
 
 import { getTranslation, type I18nClient } from '@payloadcms/translations'
 import { Link } from '@payloadcms/ui'
-import { formatAdminURL } from '@payloadcms/ui/shared'
+import { formatAdminURL } from 'payload/shared'
 import React from 'react'
 
 export const RscEntrySlateCell: React.FC<