Replace usage of manager with interface and add services

api/client.go

api/precan.go

api/user.go

bindings/group.go

bindings/ud.go

cmd/group.go

cmd/ud.go

cmix/remoteFilters.go

go.mod

go.sum

groupChat/group.go

groupChat/groupStore/group.go

groupChat/groupStore/store_test.go

groupChat/makeGroup.go

groupChat/makeGroup_test.go

groupChat/manager.go

groupChat/manager_test.go

groupChat/messageReceive.go

groupChat/processor.go

groupChat/receive.go