Improve class import and strict typing for generated migration class

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

core/Command/Db/Migrations/GenerateCommand.php

@@ -40,8 +40,12 @@ class GenerateCommand extends Command implements CompletionAwareInterface {
 
 	protected static $_templateSimple =
 		'<?php
+
+declare(strict_types=1);
+
 namespace {{namespace}};
 
+use Closure;
 use OCP\DB\ISchemaWrapper;
 use OCP\Migration\SimpleMigrationStep;
 use OCP\Migration\IOutput;
@@ -53,28 +57,28 @@ class {{classname}} extends SimpleMigrationStep {
 
 	/**
 	 * @param IOutput $output
-	 * @param \Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
 	 * @param array $options
 	 */
-	public function preSchemaChange(IOutput $output, \Closure $schemaClosure, array $options) {
+	public function preSchemaChange(IOutput $output, Closure $schemaClosure, array $options) {
 	}
 
 	/**
 	 * @param IOutput $output
-	 * @param \Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
 	 * @param array $options
 	 * @return null|ISchemaWrapper
 	 */
-	public function changeSchema(IOutput $output, \Closure $schemaClosure, array $options) {
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options) {
 {{schemabody}}
 	}
 
 	/**
 	 * @param IOutput $output
-	 * @param \Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
+	 * @param Closure $schemaClosure The `\Closure` returns a `ISchemaWrapper`
 	 * @param array $options
 	 */
-	public function postSchemaChange(IOutput $output, \Closure $schemaClosure, array $options) {
+	public function postSchemaChange(IOutput $output, Closure $schemaClosure, array $options) {
 	}
 }
 ';