Generalize hash indexes to all data types

[mavam]

This makes it possible to use #index=hash on all data types.

[tobim]

I think we should have at least 2 more unit tests, maybe for address_type and vector_type. Sure these cases aren't very realistic, but the user interface supports them.

[mavam]

I've added another unit for sets and merged the changelog entries.

Adding another unit test for set would not add much value in my opinion, as it would only test that the factory dispatches for that type to the hash index. Since hashing the views is orthogonal as well, I would argue we have good coverage for now.