Fix the duplication of settings for file_link field formatter

I've debug the issue further.
Duplicate form is appearing because we are returning $form in the field formatter.
When call comes to field formatter, it already has all the options in the form. See https://git.drupalcode.org/project/drupal/-/blob/11.x/core/modules/views...

Once we return $form as it is, it gets merged into existing form array.
Line 540-542 https://git.drupalcode.org/project/drupal/-/blob/11.x/core/modules/views...

This is causing the duplicate form fields.

I believe returning empty array should fix the problem.

Left some comments after reading #30 but am tagging for summary update as proposed solution doesn't seem to line up.