[Task] Add mimeType to asset grid options (#651)

* Add mimeType to asset grid.

* Add Doc for predefined_columns

doc/10_Extending_Studio/05_Grid.md

@@ -174,4 +174,20 @@ final readonly class MetadataCollector implements ColumnCollectorInterface
         ];
     }
 }
+```
+
+### Predefined Columns
+You can define what columns should be visible by default in the grid by modifying the `pimcore_studio_backend.grid.asset.predefined_columns` parameter in your `config.yaml` file.
+
+Example:
+```yaml
+
+pimcore_studio_backend:
+  grid:
+    asset:
+      predefined_columns:
+        - key: id
+          group: system
+        - key: fullpath
+          group: system
 ```

src/Grid/Mapper/ColumnMapper.php

@@ -38,6 +38,7 @@
         'published' => 'boolean',
         'classname' => 'string',
         'index' => 'integer',
+        'mimetype' => 'string',
     ];
 
     public function getType(string $column): string

tests/Unit/Grid/Service/SystemColumnServiceTest.php

@@ -39,6 +39,7 @@ public function testGetSystemColumnsForAssets(): void
             'creationDate' => 'datetime',
             'modificationDate' => 'datetime',
             'size' => 'fileSize',
+            'mimetype' => 'string',
         ], $systemColumnService->getSystemColumnsForAssets());
     }