Allow exporting specific project data

[BenitoMatischen]

As a researcher, I want to be able to choose project data to export so that I can preserve important data more quickly than a full export.

Flags to toggle exporting for:

• project metadata
• files
• components
• wikis

[BenitoMatischen]

Selection of components - none, x amount, or all.
Prioritise by how active, and how recent activity is.