Verify module bookmarkability

Companion to https://github.com/insightsengineering/teal/pull/1011

Check every module for the ability to restore input states in bookmarked application.

`teal:::bookmarks_identical` may be helpful.

Every module constructor function must add `teal_bookmarkable` attribute to the resulting module.
Set the attribute to `NULL` if module was not verified. Set to `TRUE` if all inputs are restored from bookmark. Set to `FALSE` if some inputs fail to restore.

Mention the bookmarkability in the module documentation.
```
#' @section Bookmarking:
#' This module can be bookmarked (verified).
```

Do this for all module repos:
- [x] `teal.modules.general`
- [ ] `teal.modules.clinical`
- [ ] `teal.modules.helios`
- [ ] `teal.modules.hermes`
- [ ] `teal.goshawk`
- [x] `teal.ospery`

Work on branch `898_save_app_state3@main`.