Add Pathologic-like protection to Link fields

Problem/Motivation

Link fields can be configured to allow both internal and external links, which means that people might easily paste a full URL where they should use an internal link.

Proposed resolution

All URLs known to represent the same site (prod, test, local domains) should automatically convert to internal links in menus and link fields. That is, do for menu links and fields of type Link what Pathologic does for URLs in content.

I think this could most easily be done on save of link fields, converting anything

Ah, https://www.drupal.org/project/link_fix_absolute_urls already covers the 80% use case of the current domain.

Probably best to provide a feature there that extends this if Pathologic is enabled.

Leaving this issue open for Pathologic for feedback on how Pathologic would best share its configuration – API or just grabbing the configuration directly? – and for any recommendations or warnings.

Remaining tasks

User interface changes

API changes

Data model changes