Add a link between Works to document "dramatizations", "adaptation", "study guides" etc.

### Describe the problem that you'd like solved

It would be good if there was a positive way to indicate "do not merge these two works" that could be flagged up on the merge screen to prevent inappropriate merges.

For author merges, adding unique identifiers, and birthdates helps with this as it becomes more obvious if the two "John Smith" entries refer to different people who should not be merged.

There is a list of examples of when a work should be kept seperate from its related work (and when it shouldn't) here:

https://openlibrary.org/help/faq/editing#works-special-cases

* Summaries – book notes
* Dramatizations
* etc...

Some are obviously different, but e.g. a graphic novel adaptation of a classic novel might prominantly feature the name of the original author, and give no credit to the artist or others involved in the adaptation. At first glance this is not obviously different from any other version of the classic. Study notes, plays etc. similarly often get attributed to the original author, and re-use the same title.

### Proposal & Constraints

I'd suggest that for every item on the second list given at the link above, there be some way, perhaps a dropdown and input for work ids, to let you indicate that a work is a "study guide/dramatization" etc. and also to enter the work id of the "parent/source" work.

These could be checked for and flagged on the merge screen for people to double check their merge of works.

### Additional context
Open question: How would these links cope with merges that leave them pointing to redirects? Is there any way to auto-update them?

### Stakeholders