Option to not change path alias

Problem/Motivation

In D7 there was an option to avoid changes to the path alias for content changes.

Proposed resolution

Add an option to not allow the path alias to be changed, e.g. if the title changes the URL wouldn't change.

Remaining tasks

Add the option.
Add test coverage.

User interface changes

An option exists to not let the path alias be changed due to content changes.

API changes

TBD

Data model changes

TBD