Update action_domain setting with HTTPS URL

Problem/Motivation

This got flagged during a security scan of our site. The default action_domain config setting is set to http://search.usa.gov. We were required to update it since all .gov domains are supposed to be served from HTTPS, but we want to help get this patched at the contrib level.

Proposed resolution

Update the default setting.
Write an update function to change existing configuration on sites that use the module.

Remaining tasks

Write a patch
Review

User interface changes

None