Split DBStructure & View to avoid DB-calls and dependencies for basic operations

- new "Definition" classes vor DB and Views
- new "Writer" classes to create SQL definitions for DB and Views
- DBStructure & View are responsible to execute DB-querys

src/DI.php

@@ -65,11 +65,27 @@ abstract class DI
 	/**
 	 * @return Database\Database
 	 */
-	public static function dba()
+	public static function dba(): Database\Database
 	{
 		return self::$dice->create(Database\Database::class);
 	}
 
+	/**
+	 * @return \Friendica\Database\Definition\DbaDefinition
+	 */
+	public static function dbaDefinition(): Database\Definition\DbaDefinition
+	{
+		return self::$dice->create(Database\Definition\DbaDefinition::class);
+	}
+
+	/**
+	 * @return \Friendica\Database\Definition\ViewDefinition
+	 */
+	public static function viewDefinition(): Database\Definition\ViewDefinition
+	{
+		return self::$dice->create(Database\Definition\ViewDefinition::class);
+	}
+
 	//
 	// "App" namespace instances
 	//