move local Dancer2::Plugin::Auth::Extensible::Provider::DB to DPAE::Plugin::Provider::DB; bugfix for tests - requires a view table for new Provider::DB query
adapt providers for DPAE v0.600+ with plugin2 Moo architecture; realm_dsl no longer used; _get_query_params()accepts username str, not user href for consistency between internal & external calls to get_user_roles()