PoC: Guard secret attributes against leaking to the logs V2.0

[shundhammer]

Problem

Secret attributes of the wifi connection object might leak to the logs, e.g. if methods like inspect() are used.

Solution

Mark them as secret with secret_attr from YaST2::SecretAttributes.

Testing

Extended the unit tests.

Related PR

PR #1359 which used a #sanitized() method and a custom inspect() method, in effect doing the same manually that YaST::SecretAttributes does.

[coveralls]

coverage: 80.784% (+0.003%) from 80.781%
when pulling e67b7c8 on huha-fix-pw-leak-2
into 2ac81c0 on master.