Media Manager: Pagination not reset when filters are changed

Problem/Motivation

If a filter is changed in the Media Manager after it has already been paged, the pagination is not reset. This can result in assets not being found because they are on a previous page and thus skipped.

Steps to reproduce

• Upload a lot of assets, so media manager's pagination is active.
• Set a prefix to all assets but one (e.g., testfile_), rename the remaining asset to random_file.
• Filter the assets for testfile_.
• Use pagination to browse to page 2.
• Change the filter from testfile_ to random_file.
• random_file is not visible since it's placed on the first result page, but media manager still shows page 2.

Proposed resolution

When a filter is changed, reset pagination to 0.