Option to overwrite export files instead of creating a copy with _N suffix

Seems the source of this issue is that we use Drupal-managed file entities to export files. It is good for downloading the files using admin panel, but for drush commands it gives more problems than benefits.

So, my suggestion for drush command is to do writing the files directly to the filesystem.

I prepared an MR with a new function generateBulkYamlFiles() that generates files directly into the target directory, please review.

Also, noticed a problem that on each drush content:export module creates new files in the file_managed table, so this table grows for no reason, because with Drush we can operate with files directly.

So, the provided fix also fixes this problem with growing managed files list in Drupal.

Added more examples of the problem to the issue description.

Attaching a static patch file with those changes, to make it possible to use in composer until 🐛 GitLab Merge Requests Unable to Generate Incremental Patch Files Active is resolved.

Attaching a static patch file with those changes, to make it possible to use in composer until #3204538: GitLab Merge Requests Unable to Generate Incremental Patch Files is resolved.