feat: add createTableIfNotExists migration helper (#3576)

framework/core/src/Database/Migration.php

@@ -38,6 +38,25 @@ abstract class Migration
         ];
     }
 
+    /**
+     * Create a table if it doesn't already exist.
+     */
+    public static function createTableIfNotExists($name, callable $definition)
+    {
+        return [
+            'up' => function (Builder $schema) use ($name, $definition) {
+                if (! $schema->hasTable($name)) {
+                    $schema->create($name, function (Blueprint $table) use ($definition) {
+                        $definition($table);
+                    });
+                }
+            },
+            'down' => function (Builder $schema) use ($name) {
+                $schema->dropIfExists($name);
+            }
+        ];
+    }
+
     /**
      * Rename a table.
      */