Resolvers performance improvements

[ntarocco]

Currently we have implemented resolvers URLs that contain the current record pid, e.g.

`internal_location`: {
    ...
    location_pid: 1,
    location: {
        $ref: ".../resolver/internal_location/<intloc>/location"
    }
}

and then, in the resolver implementation, we first fetch the intloc by <intloc> and then fetch the location 1.
We could optimize this given that now we "control" the $ref when we create/update records by also adding the location pid.

1. ensure that on create/update we completely ignore any user input for the location field and instaed we re-create the $ref from the field location: ABC, e.g. $ref: ".../resolver/internal_location/<intloc>/location/ABC"
2. change the refs URLs and add the referenced record pid, whenever possible and makes sense.

Having both current record and referenced record in the resolver implementation function is far more flexible.