Appearance Tools support for a8c Classic Themes

[rambogenius]

Can we have our classic themes Opt into appearance tools?

Example: Twenty Sixteen theme is missing Settings and Styles: https://d.pr/i/utkkBW

[mrfoxtalbot]

For more context, this option is disabled by default but in principle, it could be enabled: https://developer.wordpress.org/themes/global-settings-and-styles/settings/appearance-tools/