Migrate security_groups_basic to tempest clients

Adds client argument to various helper methods, so methods would work in tenant
context. In these methods tenant_id is either an input or retrieved from
client's rest_client arguments
Argument tenant_id is kept for legacy reasons, but it's not needed. When
working with native clients, network_client used to be loaded with admin creds.
Since this is no longer the case, tenant_id is no longer required for most
cases, and can be deduced from client.

Change-Id: Iaaa6b3b8dde22e1dd4da604ab35211d75d0ae5c6
Partially-implements: bp:tempest-client-scenarios
Merge "Migrate security_groups_basic to tempest clients"