Add SelectAllButton to BulkActionsToolbar

[fzaninotto]

Problem

When a user selects all the records of a given page, they often want to select all the records regardless of pagination. Doing so is cumbersome as it implies browsing every page and clicking on "select all".

Solution

Add a "select all" button allowing to expand the selection to the same query (with the same filters), but without pagination.

SelectAllButton.mp4

Todo

• Make it work
• Add tests
• Add stories
• Document it

[fzaninotto]

The implementation is wrong: it won't work for a datagrid inside a ReferenceManyField. The selectAll callback must be defined at the controller level, and stored in the ListContext.