Closes #898
Closes #941

Incorporating bookmarking to teal applications. The functionality is handled by the shiny bookmarking mechanism, using the "server" mode. The new bookmark_manager module tracks bookmark history, should the user choose to create more than one in their session.

Overview

Inputs are stored with shiny's built-in bookmarking mechanism using the "server" mode.
Additional values may also be stored, which we use to "remember" filter state, filter snapshot history, and bookmark history.

literature

Using bookmarks requires that the shiny option "bookmarkStore" be set to "server". Normally this is achieved by calling enableBookmarking("server") before running the app or by setting enableBookmarking = "server" in a shinyApp call.
Here the option is set with a loading hook in teal. Furthermore, the bookmark manager will enforce this option.

Bookmarks are added to a list much like in the snapshot manager module but elements of the list are URLs pointing to bookmarked applications that open in new windows.

Current filter state, snapshot history, and bookmark history are included in the bookmark. The former two are stored by the snapshot manager, the latter - by the bookmark manager.

Note on bookmark history:
Bookmark URL is is obtained using the session$onBookmarked callback. As a result the URL is added to the bookmark list in the state manager module after the bookmark is created and so when one goes to the bookmarked application, the most recent bookmark is not on the list. This is a small price to pay for not relying on potentially unstable internal functions but it deserves a mention.

Manager modules

Prior to this PR, the filter_manager module was placed in the filter_manager_modal module. The former consisted on a single button that opened a modal dialog where the filter_manager was housed.
The snapshot_manager module was called by the filter_manager and its UI resided within the modal dialog opened by the filter_manager_modal button.

Here, the module that opened the modal is renamed to wunder_bar module. wunder_bar holds several buttons, each opening a different module. The wunder_bar server function passes values between its subordinate modules.

filter_manager and snapshot_manager are decoupled. The values that exist in the filter_manager_srv scope that the snapshot_manager needs are added to filter_manager_srv's return value and are passed to the snapshot_manager_srv function call in the wunder_bar server.
Likewise, snapshot_manager_srv returns an object needed by bookmark_manager_srv, which is passed accordingly.

Module compatibility

Some modules contain logic that precludes bookmarking. Therefore, each individual module will have to be proofed by its author and given the attribute: teal_bookmarkable = TRUE if bookmarking is possible. (The bookmarks_identical function will be helpful in checking.) teal will determine if the modules in the app support bookmarking and communicate it to the app user in the bookmark manager.

Miscellaneous

Adjusted some CSS class names and styles.

Additional changes

We know of three issues that preclude the bookmarking mechanism from working:

1. creating inputs empty (e.g. choices = NULL) and modifying them server-side using update*Input
2. hierarchical inputs where the value of the junior depends on the value of the senior
3. delayed module initiation (specific to teal)

Issue (3) is remedied by a change in the module_nested_tabs: unlike starting a naive app, when modules are initiated upon their first viewing, when restoring a bookmark, all modules are initiated on app start. This was done by @gogonzo.

Issues (1) and (2) require certain preventative measures, which is explained in detail here.
Appropriate changes have been made:

• 898 save app state version 3 teal.transform#207
• 898 save app state version 3 teal.reporter#268
• 898 save app state version 3 teal.modules.general#710
• 898 save app state version 3 teal.modules.clinical#1105
• 898 save app state version 3 teal.osprey#262
• teal.goshawk
• 898 save app state version 3 teal.modules.hermes#372
• https://github.com/insightsengineering/teal.modules.helios/pull/127

Update: in the context of teal update*Input will never be compatible with bookmarking due to teal.transform.
All dynamic inputs must be rewritten with rendering. This will be done during bookmarkability verification (issue below). In some cases the logic still makes it impossible to fully bookmark a module (e.g. teal.modules.general::tm_g_distribution).

TO DO

• Add bookmarking information to vignettes #1185
• Verify module bookmarkability #1186
• Register bookmark exclusions #1187
• Solve disk space consumption by bookmarks #1188
• [Bug]: Content in panel_group is not bookmarkable teal.widgets#238
• [Bug]: Buckets generated by draggable_buckets are not bookmarkable teal.widgets#239
• [Bug]: Bookmarking-related error teal.transform#210
• [Bug]: Bookmarking-related error 2 teal.transform#211