Add a further "mode" to only visually change the title

Problem/Motivation

The current implementation of auto_entitylabel uses the title / label field of the entity to store the title.

But there are cases where it would be helpful to not change the stored value, but alter the output (with a prefix / suffix, e.g. from tokens or a static text).

It would be great of auto_entitylabel could offer a 4th option to do that. Using tokens this way the title could be rewritten before output, but still the user would use the same field.

Some typical use cases are:

• Adding a field value from the entity as prefix or suffix
• Adding a static prefix or suffix to the title, e.g. "What means [node:title]?" if you'd like to make a question from the node title, while the user still enters the term

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes