Break the installation defaults out into their structure.

[albu-diku]

Add tests that assert the consistency of the options that are accepted by the generateconfs command line with the internal library function. Additionally assert that the library routine itself matches the defaults structure thus making the structure the definitive source of truth.

Doing so highlighted the following missing command line options which are added as of this commit:
--seafile_secret
--seafile_ccnetid

[jonasbardino]

Hmm, I have a hunch that we on purpose did not expose this option to prevent passing secrets on the command line, where they may be leak to shell history and any other local users. There's a note about the similar case for the OIDCCryptoPassphrase in mig/install/apache-MiG-template.conf.
At least we need to discuss the security implications before allowing anything like that.

[jonasbardino]

I haven't had time to review thoroughly but we definitely need to resolve the seafile_secret exposure comment before this can be merged.

[albu-diku]

Let me know which keys should be hidden and I will make the change.

[jonasbardino]

Well, anything that indicates a secret, including password/passphrase needs closer consideration. Perhaps rule of thumb for a migrid developer's guide.
For a few cases like X_salt and imnotify_password we support passing a special FILE::PATH form to read value from PATH, which makes such passing of secrets safe. Yet, that method only really works where we use the value in our own code, so that we read it on-demand through shared.configuration. For the seafile_secret and the oidc client password we need to insert the value verbatim in a conf file so that method is ill-suited.