Composer does not have 1:1 mapping of what can be the Host Distro name
and the names of supported distributions held in the Distroregistry.
The fact that the host distro `Name()` method as passed to the Weldr API
does not return the same name as what is used as distro name for
repository definitions. This makes it hard to use `distro.Distro` and
`distro.Arch` directly and rely on the values returned by them as their
name.
Add `New*HostDistro()` to all distro definitions, accepting the name
that should be returned by the distro's `Name()` method. This is useful
mainly if the host distro is Beta or Stream variant of the distro.
Change the distroregistry.Registry to contain host distro as a separate
value set when creating it using `New()` function. This value is
returned by `Registry.FromHost()` method. Determining the host distro is
handled by the `NewDefault()` function. Move the distro name mangling to
distroregistry package. Add relevant unit tests.
Signed-off-by: Tomas Hozza <thozza@redhat.com>
fba9fe1072