[Feature] Support polymorph relations in key mapping

[felabrecque]

Problem to solve

Key mapping doesn't work for polymorph relations.

At least, add a mention in the documentation (https://clonio.dev/docs/cloning-config/key-remapping.html) about that.

Proposed solution

Add a structure in the yaml file to be able to list model values with table and column reference for each of them.

Next, introspect the code to fetch this info automatically during a dump.

Who benefits?

Anyone on Laravel with a polymorph relations that needs anonymization.

[felabrecque]

Simple polymorph example.

Users and companies can each have multiple addresses.

3 tables: users, companies and addresses

The addresses table contains a polymorph reference to either an entry in the users or companies table.

If we remap the users.id key, the reference column in the addresses tables won't work without also being remapped.