Nigeria: Switch to Wikidata for membership data

[tmtmtmtm]

Currently our primary source (for both the House of Representatives and Senate) is the official site, via https://morph.io/everypolitician-scrapers/nigeria-national-assembly

The official site is, however, not a particularly good source of data. Many current members aren't present on the list pages (and thus their individual pages need to be specified manually), occasionally don't even have pages at all, are inconsistent in how data is presented etc.

Therefore we want to switch this to import from Wikidata P39 (position held) records, which we will then feed via prompts when the official website changes, as well as enabling people with local knowledge (including EiE) to keep the data more correct.