feat(types): introduce generic Hit type

[francoischalifour]

This introduces a new generic Hit type that infers values for records' highlighting and snippeting results.

[Haroenv]

looks good, but I think you used it in too many places, getObject(s) & browse don't have highlighting

[francoischalifour]

We used it pass ObjectWithObjectID here but it was already taken care of in SearchResponse, so we had it passed twice. This was not an issue since this type is just adding objectID another time.

[Haroenv]

looks very good!

In the future I'd love to play with attributesToRetrieve & attributesToHighlight deciding which keys get responded, although I'm not sure if you can get all of that statically (since it could be a setting)