scripts: Factorize option parsing sans 'GUIX_BUILD_OPTIONS'.

scripts: Factorize option parsing sans 'GUIX_BUILD_OPTIONS'.

* guix/scripts.scm (parse-command-line): Add #:build-options? parameter
and honor it.
* guix/scripts/challenge.scm (guix-challenge): Use 'parse-command-line'
with #:build-options? #f instead of 'args-fold*'.
* guix/scripts/gc.scm (guix-gc): Likewise.
* guix/scripts/graph.scm (guix-graph): Likewise.
* guix/scripts/hash.scm (guix-hash): Likewise.
* guix/scripts/lint.scm (guix-lint): Likewise.
* guix/scripts/refresh.scm (guix-refresh): Likewise.
* guix/scripts/size.scm (guix-size): Likewise.
* guix/scripts/weather.scm (guix-weather): Likewise.