Add search results from multiple sources (OCDS profiles, Extension Explorer)

[jpmckinney]

Have separate sections of the page for results from the current website versus other websites.

If I search the standard documentation, I expect to get results from that site, not from the extensions site. That said, I find it useful to see the results from the extensions site, especially when the standard documentation returns no results.

The results should be in visually distinct sections. There can perhaps be tabs to jump to the results from a different source. If the first tab contains no results, there can be a prompt to check the other tabs.