feat: avoid browser cache when logo or favicon change

See Kotahi !1523. I've passed the logo's and favicon's IDs as GET parameters where the logo and favicon are used: when one of these images is replaced, the new ID causes the browser to re-request them rather than getting them from cache.

I've also replaced articleQuery.json, cmsLayout.json, cmsPages.json and config.json with more minimal versions. These are all autogenerated files, created whenever a flax site is rebuilt; so it seems they should be gitignored and not in the repo at all -- but I don't have time to test removing them outright. They were storing data for a substantial number of example articles and other pages, but I've replaced then with files for a very minimal site with no articles. This works fine, according to my tests, and these files get replaced upon rebuilding a site anyway.