More flags for metrics, to allow easier skipping

Test::Kwalitee 1.09 now tests all the 'standard' (not extra, experimental) that Module::CPANTS::Analyse makes available, except for these tests: no_generated_files, extractable, extracts_nicely, has_proper_version, has_version, manifest_matches_dist.

The first of these (no_generated_files) cannot be run after a 'make' or './Build', as we will get false positives from the files that were generated.

The rest all need a dist.tar.gz to be present, to compare against.

It would be easier to be able to skip these tests by using flags, rather than having to hardcode the names themselves (so as to give you more flexibility in the future to add more metrics).