Get the core file location from config

When using Solr and Docker, it's common for files to actually live in a different location than where the instance path is.

To overcome this, it's now possible to set the `solr_path`, as the path where the files should live according to Solr.

src/Traits/CoreTraits/CoreAdminTrait.php

@@ -50,7 +50,8 @@ public function coreCreate($core, $configStore): bool
         $action = $this->admin->createCreate();
 
         $action->setCore($core);
-        $action->setInstanceDir($configStore->instanceDir($core));
+        $path = SolrCoreService::config()->get('solr_path') ?? $configStore->instanceDir($core);
+        $action->setInstanceDir($path);
         $this->admin->setAction($action);
         try {
             $response = $this->client->coreAdmin($this->admin);