[6.x] Asset container actions

[jacksleight]

This PR adds actions for asset containers, mirroring #10471 and #13137.

<?php

namespace App\Actions;

use Statamic\Actions\Action;
use Statamic\Contracts\Assets\AssetContainer;

class UploadArchive extends Action
{
    public function visibleTo($item)
    {
        return $item instanceof AssetContainer;
    }

    public function run($items, $values)
    {
        $container = $items->first();

        // ...
    }
}

Notes:

• Collections put actions and actionUrl on the page as top level props. Containers go inside the existing container object as actions and actions_url, because Browser.vue only receives container.
• Browser.vue is shared with the asset fieldtype's selector, which overrides the #header slot, so container actions never show up inside a fieldtype.
• On completion, collections do a full router.reload(). Containers refresh the listing in place instead.
• Called it ContainerActionController rather than AssetContainerActionController to match FolderActionController.
• collections/Show.vue has an afterActionSuccessfullyCompleted method that nothing calls. The ItemActions there binds no @completed and the page doesn't use the HasActions mixin, so collection actions didnt fire toasts. That's also wired up now.

[duncanmcclean]

Nice! 🔥

Out of curiosity, what's your use case for asset container actions?

[jacksleight]

I have a project where the client needs to upload results exports from running event time tracking systems. They're ZIP files that contain HTML/CSS/JS files as well as CSVs and PDFs. The files all link to each other and would get sanitised or could get disorganised if uploaded individually. There are also two different systems with different file structures.

So to ensure everything always lands in the right place and is structured correctly I've built an action that lets them upload the ZIP directly, along with the event title/date, then the action creates the right folder structure and extracts the files (it also does its own checks to make sure there is nothing suspect in the ZIP).