Automatically move standard files to web folder

[maks-oleksyuk]

Summary

Inspired by the drupal/core-composer-scaffold plugin, I propose to introduce similar functionality, namely:

When using the wordpress-core-installer plugin, automatically install the index.php and wp-config.php files in the project's web directory (web_root), as well as the bedrock-autoloader.php file in the mu-plugins directory.

These files do not change often, so I think they can be moved. The wp-config.php file contains a comment not to edit this file.

If the files are installed automatically, it allows you to include these files in .gitignore and not worry about them, which is useful for CI

Additional context

Also, this functionality allows you to include the web folder in .gitignore and leave it under the full control of composer