Feature: SearchKit actions for Add to/Remove from batch

It would be really neat to get the search actions for "Add to batch" and "Remove from batch" working with a SearchKit listing of contributions.

I've had a go adding a URL route to the existing search task in order to get picked up as a "legacy search task" and it doesn't quite work.

First I think there is an issue with the controller class being hard-coded for SearchKit contribution tasks (in this line: https://github.com/civicrm/civicrm-core/blob/6f61a39b3cfb45c3a56b2557203660c69ff2bdab/ext/search_kit/Civi/Api4/Action/SearchDisplay/GetSearchTasks.php#L196 )

Then I think CRM_Civigiftaid_Form_Task_AddToBatch needs some tweaks to load nicely with the contribution ids passed as a request param.

Hoping to find some more time this week to get as far as an MR.