show final solution in --no-download --fix-missing mode

show final solution in --no-download --fix-missing mode

This commit moves the creation of the fetcher and with it the
calculation of the filenames before the code generation the various
lists detailing the solution. This means that simulation comes even so
slightly closer to a real run as it will require and parse the package
indexes for filenames and queuing of URIs, so that a simulation "using"
an unavailable download method actually fails now.

The real benefit of this change is through that the rather special but
nontheless handy --no-download --fix-missing mode now actually shows
what the solution is it will apply to the system rather than the
solution it would if it could download all not-downloaded packages.