Make the default user being used for connection a generic concept #105
Description
Currently the concept of user used for connecting is bound to the ssh connector.
As a result a lot of generic processes use this information in a "hardcoded" way using connector(:ssh).ssh_user to know which user is used, and whether privileges escalation is needed or not.
The user concept should not be specific to this connector, and should be moved at a generic level to avoid such a dependency on the ssh connector.