Provide upgrade path to Domain path prefix feature

Problem/Motivation

The Domain module now supports a path prefix per hostname, see #3575947: Support a path prefix for Domain records to allow a single hostname to host multiple domains

Proposed resolution

Provide upgrade path to Domain path prefix feature

Remaining tasks

1. Write a merge
2. Review
3. Commit

User interface changes

None

API changes

None

Data model changes

The country_path/domain_path third party setting is moved to the domain_record path_prefix property