Refactor of micropub request handling

Trying to organise the code better. It now temporarily doesn’t support
update requests. Thought the spec defines them as SHOULD features and
not MUST features. So safe for now :)

app/Providers/MicropubServiceProvider.php

@@ -0,0 +1,26 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Providers;
+
+use App\Services\Micropub\CardHandler;
+use App\Services\Micropub\EntryHandler;
+use App\Services\Micropub\MicropubHandlerRegistry;
+use Illuminate\Support\ServiceProvider;
+
+class MicropubServiceProvider extends ServiceProvider
+{
+    public function register(): void
+    {
+        $this->app->singleton(MicropubHandlerRegistry::class, function () {
+            $registry = new MicropubHandlerRegistry;
+
+            // Register handlers
+            $registry->register('card', new CardHandler);
+            $registry->register('entry', new EntryHandler);
+
+            return $registry;
+        });
+    }
+}