VBO Export error

Problem/Motivation

Hi, after upgrade to 1.4.13, we got error when exporting:

It is because we have enabled "batch" processing for VBO, while the latest version of class ContentBulkExport is trying to output the zip file in the views AJAX response.

Steps to reproduce

Create a view with VBO, enable the "Export Content" action.
Check the box Process in a batch operation.

Proposed resolution

The ViewsBulkOperationsActionProcessor will assign the context property, which holds the 'batch' operation option.
The executeMultiple method could response accordingly if $this->context->batch is true or not.
However, in this case ContentBulkExport has to extends from ViewsBulkOperationsActionBase, which makes VBO become a dependency for this module.
Maybe there is better way to check if the current action is from VBO or a simple core Action.

Remaining tasks

N/A

User interface changes

N/A

API changes

N/A

Data model changes

N/A