Better handling of indentation

[vknabel]

Currently this extension reads the editor setting for the indentation and passes it to swiftformat.

This behaviour might make sense if no indentation rules were provided in the config and if the user stays to vscode's defaults. But as it belongs to the responsibility of swiftformat, the current behaviour is misleading wrong.

=> The extension should tell VS Code which indentation rules it should follow by reading the provided config (if there is any).