Improve performance and code readability.

Problem/Motivation

The ViewsBulkOperationsBulkForm class is serving two different purposes but only one at a time (admin config form or views form). No point loading all the dependencies every time, also the code would be more readable if this could be split to 2 files. Also

Proposed resolution

Use traits and execute relevant methods in the main class constructor if possible.
Distinguishing between the two forms can be made in the create function using \Drupal::routeMatch()->getRouteObject()->getDefault('view_id');

API changes

There will be no API changes resulting from the solution.