* feat(config):read config/defaults with authentication
This change allows to use defaults and config files from a protected GitHub repository.
The options `--customConfig` and `--defaultConfig` already allowed to provide a link to an uprotected file.
Now, by passing a value in the form `<hostname>:<token>` to parameter `gitHubTokens` (this parameter can be passed multiple times) a token can be provided for dedicated hosts.
This makes it possible to use a link like
`https://api.github.com/repos/SAP/jenkins-library/contents/resources/my-defaults.yml?ref=master`
as reference to a default file or similarly as reference to a configuration file.
* update generation to allow protected config/defaults
* fix CodeClimate issues
* update missing generations
* Provide getters for stdout, stderr on ShellRunner, ExecRunner
we need that in order to set the streams back in case we have to scan the command
output ourselvs during some function calls.
* Allow retrieving exit code from command execution
This will be helpful to derive error categories in case
an executable provides context-specific error codes.
* make sure that we always have a non 0 exit code for errors
ExecMockRunner and ShellMockRunner both needs an environment. "Extending"
here leads to "subclasses" for both cases. That is more long-winded since
it could be.
I don't understand why there should be a two dimensional array.
When dealing with envs we have normally a list containing entries like
[]string{"DEBUG=true", "HOME=/home/me"}
Having two dimensional env arrays would mean to have several alternate
environment in the tests at the same time. Don't think there is a need
for that.
