Add test proving filters apply to projects pagination

Hi,

The current live site doesn't seem to honour the filters on the projects page when fetching later pages. It looks like this was reported in #564 and fixed in #565 (but hasn't yet been deployed). It took me a little moment to find that out, though - it might have been a little easier to determine if it'd already been fixed if it had been documented in tests.

This PR adds some tests to complement the fix in #565.

Thanks,
Rowan