Fix for: https://meta.discourse.org/t/our-components-stop-working/181580?u=osama.
This fixes an old hidden bug that was exposed in cf0192018e. The bug is that we call the `Stylesheet::Manager.stylesheet_details` method with the `target` arg as `:mobile_theme` when we want to retrieve a theme component's mobile CSS. The problem is that this `target` value will at some point be looked up in the `Theme.targets` enum which doesn't have a `:mobile_theme` key, instead it has `:mobile` key.
This commit adds a step that removes the `_theme` suffix in the `Theme.list_baked_fields` method to fix this problem.
c0e2fdd200