This reverts commit 20780a1eee.
* SECURITY: re-adds accidentally reverted commit:
03d26cd6: ensure embed_url contains valid http(s) uri
* when the merge commit e62a85cf was reverted, git chose the 2660c2e2 parent to land on
instead of the 03d26cd6 parent (which contains security fixes)
* the post_actions table has no FK to users, so if a user has been
deleted we may end up with dangling post_action records, which then
interferes with the bookmarks migration because bookmarks DO have
an FK to users
The main thrust of this PR is to take all the conditional checks based on the `enable_bookmarks_with_reminders` away and only keep the code from the `true` path, making bookmarks with reminders the core bookmarks feature. There is also a migration to create `Bookmark` records out of `PostAction` bookmarks for a site.
### Summary
* Remove logic based on whether enable_bookmarks_with_reminders is true. This site setting is now obsolete, the old bookmark functionality is being removed. Retain the setting and set the value to `true` in a migration.
* Use the code from the rake task to create a database migration that creates bookmarks from post actions.
* Change the bookmark report to read from the new table.
* Get rid of old endpoints for bookmarks
* Link to the new bookmarks list from the user summary page
