Adding filters to allow alternate sidebar storage for registered sidebars

[welcher]

Currently sidebars are stored in the sidebars_widgets option in the database which for site with many sidebars can be very inefficient.

I would like to propose a means of being able to change how the information is stored.

I have introduced two filters that allow a user to have access to the information being saved or requested. This is backwards compatible but gives the option of using, for example ,a post type to store the data.

[welcher]

Related #32470, #32474

[DrewAPicture]

Some notes:

• These filter names need a little bit of work. They evaluate as booleans but the filter names don't really reflect that
• If we do end up keeping the boolean returns by default, the check on what is currently the 'sidebars_widgets_custom_storage' hook could just easily be a strict boolean check

On the hook docs:

• The duplicate hook comment should be one line, e.g. /** This filter is documented in ... */
• The duplicate hook comment only needs to mention the path to the file
• Hook doc summaries should end with a period
• @since versions should be the 3-digit x.x.x style, e.g. 4.4.0
• Multiple types in phpDoc should use a pipe, e.g. |

[westonruter]

@welcher As opposed to introducing new filters, why not just utilize pre_option_sidebars_widgets filters?

[welcher]

Replying to westonruter:

@welcher As opposed to introducing new filters, why not just utilize pre_option_sidebars_widgets filters?

Currently that would be the best approach, however I like the idea of having a hook before the get_option() call happens so we can decouple the get/set process completely from the calls to the *_option methods. I think this provides more flexibility moving forward.

I also found the storage process with the pre_update_option_sidebars_widgets filter to be a little counter-intuitive as you have to return $old_value to short circuit the update_option call.
.

[welcher]

Updated patch for better hook names, inline doc corrections and a more integrated approach to retrieving the widgets

[wonderboymusic]

32987.3.diff​ refreshes after [33746]

[welcher]

Updated docs and corrected logic for checking for boolean filter results

[welcher]

Adding unit tests

[welcher]

I have added some unit tests as per the Slack discussion. Am happy to add more or make any further changes as needed.

[welcher]

Updated unit tests with doc block and better method naming

[welcher]

Closing based on where Gutenberg is headed in Phase 2,