[9.x] Added soft deleted to Meilisearch (OOTB included)

[kichetof]

This PR add soft deleted for Meilisearch indexes.

1. Out of the box: artisan scout:index 'App\Models\Users' will add filterable attributes __soft_deleted when model already use SoftDeletes trait and without any configuration 🤩
2. Sync index: when you add SoftDeletes after index creation, you need to declare class in your scout config file. Instead of writing some repetition of:

\App\Models\User::class => [
    'filterableAttributes' => ['__soft_deleted']
],

You can simply write: \App\Models\User::class => [], or, more compact: \App\Models\User::class,

Your scout config file should look like:

'meilisearch' => [
    'host' => env('MEILISEARCH_HOST', 'http://localhost:7700'),
    'key' => env('MEILISEARCH_KEY', null),
    'index-settings' => [
        // full declaration
        \App\Models\User::class => [
            'filterableAttributes' => ['__soft_deleted']
        ],
        // compact declaration
        \App\Models\User::class => [],
        // more compact
        \App\Models\User::class,
    ],
],

Don't worry about multiple attributes definition, I tested a lot of times by querying Meilisearch index settings, and only one definition will be set.

[driesvints]

Hey @kichetof. Thanks for these, I just released them as v9.6.0. Do you maybe feel up to send a PR to the docs for this PR and #671?

https://laravel.com/docs/9.x/scout#configuring-filterable-data-for-meilisearch

[kichetof]

Hello @driesvints I saw that Taylor updated before me, too fast for me 😎
I sent this PR to add index, delete-index and delete-all-indexes.

On writing the doc, I've see that delete-index couldn't receive a FQCN, I'll send a PR to update that.