Deprecated exercises shouldn't be able to be part of core

[amscotti]

Based on exercism/javascript#433, I feel that configlet lint should error on any exercise that has "core": true but also is "deprecated": true. Right now, with this configuration it blocks someone from moving on to the next exercise in the track.

[nywilken]

@amscotti thanks for opening up this issue. This seems like a bug on the Exercism backend side as well if it is indeed showing exercises which are set to be unlocked by deprecated exercises. @iHiD ☝️

None the less, I agree that we should have a check for this case. If anything two checks. One that deprecated exercises are not core, two that an exercise is not set to be unlocked by a deprecated exercise.