Merge all the CSVs into one

[h-m-f-t]

This repo houses 1_govt_urls_full.csv but also breaks government types into their own files.

Taking this approach increases our and any contributors' maintenance burden (since updates have to occur in multiple places) and it's prone to error (since the updates have to be made to multiple places the same way). The core benefit of multiple files (interested users only have look one place) is still attainable by analyzing the CSV in tools like Excel or Sheets, or programmatic means. GitHub also has a built-in viewer for flat files when you prepend flat to github.com. For this repo, see https://flatgithub.com/GSA/govt-urls?filename=1_govt_urls_full.csv&sha=a5d35ef0fb41d207ed1b3c2a1b5d026dd7c5f83e.

We should just maintain one file.