Make singleton AccountFactory capable of filtering by capabilities
Make singleton AccountFactory capable of filtering by capabilities

The JoinChatRoomDialog uses this to filter for accounts that support
multi-user conversations.

Reviewed-By: David Edmundson

leonhandreke/ktp-common-internals,leonhandreke/ktp-common-internals,KDE/ktp-common-internals,KDE/ktp-common-internals,KDE/ktp-common-internals,leonhandreke/ktp-common-internals