[Revise subclass] 'developmental and epileptic encephalopathy'

[nicolevasilevsky]

Mondo term (ID and Label)
'developmental and epileptic encephalopathy'

Suggested revision and reasons
Per the epilepsy workshop, this class is not always a Mendelian disorder. Need to review the superclass assertions.

Also, it is not always a neonatal/infantile epilepsy syndrome (cases can have later onsets)

related to:
#8200
#8161