N°3526 - Clean up pass on UIBlocks

- Move UIBlock::ENUM_BLOCK_FILES_TYPE_XXX to iUIBlock
- Add PHPDoc
- Remove Object return type hint on overloadable methods
- Add scalar return type hint
- Add type hint on parameters

sources/application/UI/Base/Layout/Dashboard/DashboardLayout.php

@@ -48,7 +48,7 @@ class DashboardLayout extends UIBlock
 		return $this;
 	}
 
-	public function GetSubBlocks()
+	public function GetSubBlocks(): array
 	{
 		return array_merge($this->aDashboardRows, [$this->oToolbar]);
 	}