Add ability to remove previously parsed resources no longer getting parsed

It'd be nice to optionally be able to remove previously parsed resources that were not included as part of a full re-parsing.

Remove may mean delete, but more likely assignment of a non-"publish" post status.

Two examples where this is useful:

1. Inadvertently (or intentionally, but with later misgivings about doing so) including a file in a parsing that should not have been included. (In this case you may actually want the parsed resources deleted.)
2. Functions, hooks, classes, etc that no longer exist and that you no longer want to have listed/available as if they did. (In this case you probably don't want to delete as there may be meta data added to these resources after they were parsed, such as comments, etc.)

This could be a wontfix under the belief that it's the parser user's responsibility to handle this. In which case, the parser user would probably hook 'wp_parser_import_item_post_data' and forcibly set post_modified for everything sent its way (since currently, wp_update_post() is not called if there wasn't a change in the post object data). Then after parsing, a script could remove anything not modified since the known parsing datetime (and anything related to them).

But shouldn't the parser have some responsibility (or capability) here if it does updates?

Start by tracing the parser's full re-parsing flow and the wp_parser_import_item_post_data hook, including when wp_update_post() is called. Review how parsed resources are identified and determine whether the intended behavior is deletion, assigning a non-"publish" status, or leaving cleanup to a script; the issue does not yet establish a chosen behavior.