p-groups with derived subgroup of prime order are covered by theory

[limakzi]

By Sandling theorem, their group algebras provide full information about the group

[margollo]

The idea of the functions IsCoveredByTheory and IsCoveredByTheoryAllFields is to cover theoretical results not covered by other invariants which are tested before in the main functions and in principle this class is handled by SandlingInfo. But it is true this will not work if the input group is too big for IdGroup, so it would make sense to test the criterion also in the Covered functions. This effects also other classes of groups, but it sounds reasonable to include them in the Covered functions. Will be done in next version, thanks for the observation.