This commit:
- Adds KojiResolver class and KojiResolver tests.
- Changes the GenericResolver and its subclasses to pass base_module_mmds
instead of base_module_nsvc to get_buildrequired_modulemds. This is needed,
because KojiResolver needs to access XMD section of base module.
- Implements KojiResolver.get_buildrequired_modulemds to ask Koji for list of
modules tagged in the Koji tag and return their modulemds.
This removes support for default_modules_url in the Platform XMD and
gets the list of default name:stream combinations to include in the buildroot
from https://pagure.io/releng/fedora-module-defaults.
Addresses #1402
A base module can set xmd.mbs.default_modules_url, which contains a
URL to a list of modules in the format of name:stream separated by
new lines. When a module buildrequires this base module, the list
of default modules are added as buildrequires of the module automatically
unless there are conflicting streams or the default module is not
in the MBS database.
These module builds will basically act as metadata-only module builds.
This will be more useful as additional features stem from these types
of builds.
