Export only selected page access statistics

[juliankehne]

Motivation

Currently the csv export of page access statistics always exports everything (languages, total access etc.). However when a user deselects languages or other data (Offline Accesses, WebApp Accesses, Total Accesses) it should also only export this data as a csv, since that is the data the user wants to see.

Proposed Solution

Export the page access statistics based on the 'Shown Languages' and 'Access' checkboxes selected.

Alternatives

Keep it as it is.

User Story

As a manager I want to export only the selected languages so that I don't have to do more work after the export.

Additional Context

Design Requirements

Related Issues

Discussed in #3133