Move `interface.utils.eval_results` to `interface(.base)`

[mih]

There is pretty much no Interface implementation without it, just like with build_doc. IMHO both pieces should live in the same place.

This would make the common

from datalad.interface.base import (
    Interface,
    build_doc,
)
from datalad.interface.utils import (
    eval_results,
)

just be

from datalad.interface.base import (
    Interface,
    build_doc,
    eval_results,
)

an argument could be made to consolidate all (more or less strictly) required pieces in datalad.interface. Looking like this:

from datalad.interface.base import (
    Interface,
    Parameter,
    build_doc,
    datasetmethod,
    eval_results,
)

[adswa]

done in #7170

[yarikoptic-gitmate]

Issue fixed in 0.18.0