Add subtype scanning module filter and add common TypeScanning type.

[big-andy-coates]

It's already possible to limit the main scan for schema types by module name. Add the same functionality for subtype scans.

This then highlights a common pattern for both types of scans: filter by module and filter by package. So move this into its own type.

Reviewer checklist

• Ensure relevant issues are linked (description should include text like "Fixes #")
• Ensure any appropriate documentation has been added or amended

[coveralls]

Coverage increased (+0.3%) to 94.007% when pulling 9c93aa9 on subtype_modules into fde4cf4 on main.