Use path-spec instead of path for module-not-found errors

[ugexe]

The path portion of the path-spec is often not enough to debug what wasn't found. This change includes the entire path-spec when giving an error for e.g. use NotFound;

$ install/bin/perl6 -I . -e 'use NotFound;'
===SORRY!===
Could not find NotFound at line 1 in:
    file#/Users/ugexe/repos/rakudo
    inst#/Users/ugexe/.perl6
    inst#/Users/ugexe/repos/rakudo/install/share/perl6/site
    inst#/Users/ugexe/repos/rakudo/install/share/perl6/vendor
    inst#/Users/ugexe/repos/rakudo/install/share/perl6
    ap#
    nqp#
    perl5#

It might be best to remove the empty repos from output, but they are used in determining the other repo's repo-id so their removal should be considered outside of this PR.