public and private package configuration

[nbargnesi]

This adds two new methods to lib.common.abstracts.Package:

1. configure(target)
2. configure_from_data(target)

Both methods are optional.

If a package doesn't provide a configure method, it's logged but ignored. Likewise if no private configuration is importable from data.packages.<package_name>, it's also logged but ignored.

With this PR, packages like DOC_ANTIVM can separate 40 lines of configuration into a separate method, and provide a way to mask sensitive configuration.

[doomedraven]

for what do you need the name of the package?

[nbargnesi]

for what do you need the name of the package?

The package name identifies the module to import when configure_from_data is called.

In the test case, the package name is configuration_package. So the module we look for is data.packages.configuration_package.

[doomedraven]

nice feature thank you