restructure supertoken id; add support for db cluster

cmd/mytoken-server/main.go

cmd/mytoken-server/mytoken-setup/setup.go

config/example-config.yaml

internal/config/config.go

internal/db/cluster/cluster.go

internal/db/db.go

internal/db/dbrepo/accesstokenrepo/accessToken.go

internal/db/dbrepo/authcodeinforepo/authcodeInfo.go

internal/db/dbrepo/eventrepo/event.go

internal/db/dbrepo/supertokenrepo/supertoken.go

.../db/dbrepo/supertokenrepo/supertokenrepohelper/helpers.go

shared/supertoken/event/event.go

shared/supertoken/pkg/stid/stid.go

shared/supertoken/pkg/stid/stid_test.go

shared/supertoken/pkg/supertoken.go

shared/supertoken/pkg/supertoken_test.go

shared/supertoken/restrictions/restriction.go

shared/supertoken/superTokenHandler.go