Spec suggestion: also crawl spec with Reffy and report potential issues

[tidoust]

The spec suggestion mechanism generates and reports updates to index.json. It would also be useful to crawl the resulting spec with Reffy so that we may also review would-be crawl extracts, noting that:

1. This may generate a lot of data, and the more data to review, the less likely that we'll do a good job at reviewing the data.
2. Reffy does not run tests on the data per se, these tests are rather done in Webref. It would seem useful to validate the extracted IDL combined with the IDL defined in other specs for example... but we would need Webref data for that.

[tidoust]

An example of when running IDL tests could be useful info is the recently added Device Attributes API, which re-defines the interface NavigatorManagedData that is already defined in Managed Configuration API. In such instances, we might want to suggest fixes to the spec before they get added to the list, or at least know that we're going to break data curation in Webref.