Provide special thought to headful-only search results

[gselzer]

If a particular SearchResult wraps a ModuleInfo, we can know whether the Module it creates can be run headlessly. We might want to protect against running headful-only Modules in a headless environment, by e.g. disabling these results.

[gselzer]

See [this comment] for a potential solution that was outside the scope of that PR.

[gselzer]

Also check out the available flags. We might want to be using ItemIsEnabled...