Factor-packman:pkg-sign

From Zen/-/ackers

The pkg-sign command allows the package-creator to digitally sign the package so that other users of the package can verify authenticity of the package.

The pkg-sign word has the following signature:

   pkg-sign ( pkg-location seq -- )

   :: pkg-location: the local path to the package tarball to sign as a string.
   :: seq: a sequence (list) of options to be used by the pkg-sign word.