Jetpack options: audit of autoloading

Autoloaded Jetpack options can be quite big, and there's a good number of them, which creates a performance hit, but this isn't always justified.

Following the concept of only executing the code of enabled modules, it will help to only load the opions of only enabled modules, which cannot be done if they're all autoloaded. Also, some (most?) Jetpack modules don't require the performance boost of option autoloading, e.g. because they operate in the background.

Please review when in the code options are loaded and reduce the number of autoloaded options as much as possible.

Start by tracing where Jetpack options are loaded and which modules enable them, then inventory the autoloaded options across the relevant module code. Done means reducing autoloaded options where the issue's performance rationale allows it and verifying that enabled modules still load their required options correctly.

Written by the indexing model from the issue text.