Make amp-options an autoloaded option

[westonruter]

On accessing the frontend, there is a persistent query for the amp-options option:

Given that this option is always queried with each request, the option should be made autoloaded (part of alloptions).

[MackenzieHartung]

Note: For now, Analytics will be decoupled from the other AMP options stored, and remain not autoloaded.

[westonruter]

We should make sure that any related WordPress core issues related to autoloaded options don't cause headaches here. I recall at a time that there was a bug in core where multiple updates to an autoloaded option could cause some updates to be lost. If this issue is still current, then it will be a problem for the AMP plugin since amp-options stores multiple settings that could receive more than one update in a request.