new: [meta_field] API improved

- simple way to add metafields added
  - simply pass a list of meta_fields to the object about to be saved
  - the only fields required are: template_uuid, template_version, field, value
Example for an individual:

```
{
  "first_name": "Andras",
  "last_name": "Iklody",
  "email": "[email protected]",
  "alignments": {
    "organisation": [
      {
        "uuid": "9d4d7913-2602-4333-8440-c78b7f92eca3",
        "name": "Iglocska.eu"
      }
    ]
  },
  "meta_fields": [
    {
      "field": "perm_mattermost",
      "value": true,
      "template_uuid": "447ded8b-314b-41c7-a913-4ce32535b28d",
      "template_version": 2
    }
  ]
}
```

src/Controller/Component/CRUDComponent.php

@@ -458,6 +458,9 @@ public function add(array $params = []): void
                 $massagedData = $this->massageMetaFields($data, $input, $metaTemplates);
                 unset($input['MetaTemplates']); // Avoid MetaTemplates to be overriden when patching entity
                 $data = $massagedData['entity'];
+                if (isset($input['meta_fields'])) {
+                    unset($input['meta_fields']);
+                }
             }
             $data = $this->Table->patchEntity($data, $input, $patchEntityParams);
             if (isset($params['beforeSave'])) {
@@ -568,10 +571,35 @@ private function saveMetaFields($id, $input)
         $this->Table->saveMetaFields($id, $input, $this->Table);
     }
 
+    private function handleSimpleMetaFieldInput($allMetaTemplates, $input, &$cleanupMetaFields)
+    {
+        $input['MetaTemplates'] = [];
+        foreach ($input['meta_fields'] as $metaField) {
+            foreach ($allMetaTemplates as $metaTemplate) {
+                if ($metaTemplate->uuid != $metaField['template_uuid'] || $metaTemplate->version != $metaField['template_version']) {
+                    continue;
+                }
+                foreach ($metaTemplate['meta_template_fields'] as $mtp) {
+                    if ($mtp->field == $metaField['field']) {
+                        // I feel dirty. I'm sorry.
+                        $input['MetaTemplates'][$metaTemplate->id]['meta_template_fields'][$mtp->id]['metaFields']['new'][] = $metaField['value'];
+                        $cleanupMetaFields[] = [
+                            'scope' => $this->Table->getBehavior('MetaFields')->getScope(),
+                            'field' => $mtp->field,
+                            'meta_template_field_id' => $mtp->id,
+                            'meta_template_id' => $metaTemplate->id
+                        ];
+                    }
+                }
+            }
+        }
+        return $input;
+    }
+
     // prune empty values and marshall fields
-    public function massageMetaFields($entity, $input, $allMetaTemplates = [])
+    public function massageMetaFields($entity, $input, $allMetaTemplates = [], &$cleanupMetaFields = [])
     {
-        if (empty($input['MetaTemplates']) || !$this->metaFieldsSupported()) {
+        if ((empty($input['MetaTemplates']) && !isset($input['meta_fields'])) || !$this->metaFieldsSupported()) {
             return ['entity' => $entity, 'metafields_to_delete' => []];
         }
 
@@ -580,6 +608,12 @@ public function massageMetaFields($entity, $input, $allMetaTemplates = [])
         if (empty($metaTemplates)) {
             $allMetaTemplates = $this->getMetaTemplates()->toArray();
         }
+        // handle simpler format of meta_templates via the API
+        // the idea is that integrators shouldn't have to mimic the complex format used by the UI.
+        if (isset($input['meta_fields'])) {
+            $input = $this->handleSimpleMetaFieldInput($allMetaTemplates, $input, $cleanupMetaFields);
+            $entity->cleanupMetaFields = $cleanupMetaFields;
+        }
         if (!empty($entity->meta_fields)) {
             foreach ($entity->meta_fields as $i => $metaField) {
                 $metaFieldsIndex[$metaField->id] = $i;
@@ -738,11 +772,28 @@ public function edit(int $id, array $params = []): void
                     throw new NotFoundException(__('Could not save {0} due to the marshaling failing. Your input is bad and you should feel bad.', $this->ObjectAlias));
                 }
             }
+            $cleanupMetaFields = [];
             if ($metaFieldsEnabled) {
-                $massagedData = $this->massageMetaFields($data, $input, $metaTemplates);
+                $massagedData = $this->massageMetaFields($data, $input, $metaTemplates, $cleanupMetaFields);
+                if (!empty($cleanupMetaFields)) {
+                    foreach ($cleanupMetaFields as $cleanupMetaField) {
+                        $this->Table->MetaFields->deleteAll([
+                            'AND' => [
+                                'scope' => $cleanupMetaField['scope'],
+                                'field' => $cleanupMetaField['field'],
+                                'meta_template_field_id' => $cleanupMetaField['meta_template_field_id'],
+                                'meta_template_id' => $cleanupMetaField['meta_template_id'],
+                                'parent_id' => $id
+                            ]
+                        ]);
+                    }
+                }
                 unset($input['MetaTemplates']); // Avoid MetaTemplates to be overriden when patching entity
                 $data = $massagedData['entity'];
                 $metaFieldsToDelete = $massagedData['metafields_to_delete'];
+                if (isset($input['meta_fields'])) {
+                    unset($input['meta_fields']);
+                }
             }
             $data = $this->Table->patchEntity($data, $input, $patchEntityParams);
             if (isset($params['beforeSave'])) {